Glossary
Plain-language definitions of the languages, tools, and ideas that show up on developer profiles and in job descriptions.
207 of 207 terms
A
Agile
The dominant way software teams organize work: short cycles, frequent releases, and plans that adjust as the team learns.
AI agent
An AI agent is a program that uses a language model to decide what steps to take, then carries them out.
AI code review
An automated reviewer that reads a pull request and comments on it before a person does.
AI workflow
An AI workflow is a fixed sequence of steps, some run by a model, chained together to finish a task.
Amazon S3 Service
Amazon's object storage service, the standard place cloud applications keep files. Its storage units are called buckets.
Angular Framework
Google's framework for building the screens of a website, written in TypeScript. Most common in the frontends of large companies.
Anthropic
The AI company that makes Claude. Founded in 2021 by former OpenAI researchers and based in San Francisco.
API
The agreed way one piece of software asks another for data or an action. It is the contract between the screen and the server.
Architect
An engineer whose main job is deciding how a system's pieces fit together, before code gets written and as it evolves.
Automated testing
Code that checks other code. Tests run automatically on every proposed change and fail loudly when something breaks.
AWS Platform
Amazon's cloud platform, the largest by market share. Rented servers, storage, and databases, billed by usage.
AWS Lambda Service
AWS's serverless product. Small functions that run when an event fires, billed per use, with no server to manage.
Azure Platform
Microsoft's cloud platform, strongest in large enterprises that already run Microsoft software like Windows Server and Office.
B
Backend
The half of an application users never see: server code that stores data, enforces the rules, and answers requests from the screen.
Background agent
A coding agent that takes a ticket, works unattended, and comes back with a finished change for review.
Background job
Work an app runs behind the scenes after answering the user, such as sending an email or building a report.
Backlog
The ordered list of work a team intends to do but has not started, ranked by priority.
Branch
A parallel working copy of a project's code, where a change gets built without disturbing the version everyone else uses.
Brownfield
Work on a system that already exists and already has users, where every change has to keep the current behavior working.
Bug
A flaw that makes software behave incorrectly. Finding and fixing bugs is a permanent part of every developer's job.
C
C# Language
Microsoft's flagship language. It runs enterprise backends on .NET, and it powers games made in the Unity engine.
C++ Language
The heavyweight systems language behind game engines, trading systems, web browsers, and machine-learning infrastructure.
Cache
A fast temporary copy of data kept close at hand, so an application answers repeat requests without redoing the work.
CDN
A worldwide network of servers holding copies of a site's files, so visitors load pages from somewhere nearby.
Chatbot
A chatbot is a program that holds a back-and-forth text conversation, usually answering questions rather than taking action.
CI/CD
Automation that tests every proposed change and moves approved code toward live users without manual steps.
Claude Service
Anthropic’s family of large language models, and the chat assistant built on them. A peer of OpenAI’s GPT.
Claude Code Service
Anthropic’s coding agent. A developer gives it a task in plain language and it writes and edits the code.
CLI (command line interface)
A CLI, or command line interface, is a program controlled by typing text commands instead of clicking buttons.
Clone
A copy of a repository downloaded onto a developer’s own computer, with the full history attached.
Cloud
Renting servers and services from providers like AWS, Google Cloud, or Azure, in place of owning physical machines.
Cloudflare Platform
A network that sits in front of websites to speed and protect them, and a platform for running code in cities worldwide.
Cloudflare Workers Service
Cloudflare's serverless platform. JavaScript and TypeScript functions that run in hundreds of cities, close to each user.
Code editor
A code editor is the app a developer types code in. Visual Studio Code is by far the most common one.
Code review
Teammates reading and critiquing a code change before the project accepts it.
Codebase
The complete body of source code behind a product, shared and changed by the whole team.
Coding agent
A coding agent is an AI agent whose tools let it read, write, and run code, carrying out programming tasks on its own.
Commit
One saved change to code, recorded with an author, a time, and a short message describing what changed.
Compiled language
A language translated into machine instructions before it runs. Go, Rust, C++, Java, and C# are compiled.
Container
A standard package holding a program and everything it needs to run, so it behaves the same on any machine.
Context engineering
The craft of choosing what a model sees before it works: which files, which instructions, which data, and what to leave out.
Context window
The context window is the amount of text a language model can read and remember at one time.
Contribution graph
The grid of green squares on a GitHub profile. Each square is one day, and darker means more public activity that day.
Contributor
Someone whose changes were accepted into a repository they do not own. GitHub lists contributors on every repository page.
Cron job
A task set to run automatically on a schedule, like every night at 2am, with no person starting it.
Cross-platform
Building one codebase that ships as both an iPhone app and an Android app, using a framework like React Native or Flutter.
CSS Styling
The code that controls how a web page looks: colors, fonts, spacing, and how a layout rearranges on a small screen.
Cursor Platform
An AI-first code editor released in 2023. It is VS Code’s design with an AI assistant built into the core.
D
Dart Language
Google's language for building app screens. In practice, people write Dart because they are building a Flutter app.
Data center
A secure building filled with thousands of servers, plus the power, cooling, and network connections that keep them running.
Data lake
A store of raw data in every format, kept cheaply at full size so it can be analyzed later.
Data pipeline
An automated chain of steps that moves and reshapes data from where it is produced to where it is used.
Data science
Data science is the discipline of pulling answers and predictions out of a company’s data, using statistics and code.
Data warehouse
A database built for analysis rather than running an app. It answers big questions across all of a company's data.
Database
Software built to store an application's data reliably and find it fast: accounts, orders, messages, everything an app remembers.
dbt Framework
A tool for transforming data inside a warehouse using SQL, with the versioning and testing habits of software engineering.
Deploy
Putting new code onto the servers or app stores where real users run it.
DevOps
The practice of automating how software is tested, deployed, and run, so a team can ship safely and often.
Discipline
The broad area of engineering a developer works in: backend, frontend, infrastructure, machine learning, data, mobile, security, or full-stack.
Django Framework
Python's most established framework for building complete websites. Instagram and Pinterest were built on it.
Docker Platform
The standard tool for packaging software into containers, so it runs the same on a laptop and a cloud server.
Document database
A database that stores each record as one flexible document, close to the shape the application code already uses.
Documentarian
Whether a developer writes real documentation, judged by the depth of their project front pages.
Domain depth
Sustained, multi-year work in one technical area. It is the clearest form of demonstrated expertise, because it accumulates only through time.
Dynamic typing
A language feature where the kind of each piece of data gets checked while the program runs. Python and Ruby work this way.
E
Edge computing
Running code on servers physically near each user, spread around the world, for fast responses without managing regional data centers.
ETL
Extract, transform, load: the pattern of pulling data from source systems, cleaning it, and loading it into a warehouse.
Eval
A repeatable test of an AI system’s output quality, run to check whether a change made the answers better or worse.
F
Fine-tuning
Fine-tuning is additional training that adjusts a model on a smaller, specific set of examples after its main training.
Flutter Framework
Google's framework for building iPhone and Android apps from one codebase, written in the Dart language.
Fork
A personal copy of someone else's repository, made with one click. Making one involves writing no code.
Foundation model
A large general-purpose model trained once at great expense, then used as the base for many different products.
Framework
A large body of prewritten code, built in one language, that handles the repetitive parts of an application. React and Django are frameworks.
Frontend
The part of an application people see and touch: the screens, buttons, and forms running in a browser or on a phone.
Full-stack
A developer who can build both the screens people use and the server code behind them, in the same application.
G
Gemini Service
Google’s family of large language models, and the assistant built on them. A peer of OpenAI’s GPT and Anthropic’s Claude.
GitHub
The website where most of the world's software is stored, built, and shared. Much of the activity on it is public and dated.
GitHub Copilot Service
GitHub’s AI coding assistant. It suggests code inside an editor as a developer types, and it can also work as an agent.
Go Language
Google's language for fast, simple server software. Docker and Kubernetes, the tools that run the cloud, are written in it.
Google Cloud Platform
Google's cloud platform. Rented computing and storage, strongest in data and machine learning tooling like BigQuery.
GPT Service
OpenAI’s family of large language models. ChatGPT is the chat product built on top of them.
GPU
A chip built to do enormous numbers of simple calculations at once. Training and running large models depends on them.
Greenfield
Work that starts from nothing: no existing code, no users, and no decisions already made.
H
Hallucination
A confident, fluent answer from a model that is factually wrong. It reads exactly like a correct answer.
High availability
Designing a system to keep working when parts of it fail, usually by running duplicates that take over automatically.
Horizontal scaling
Handling more traffic by adding more machines that share the work, rather than upgrading to one bigger machine.
HTML Markup
The code that defines what is on a web page: the headings, the text, the images, the buttons, and the forms.
Human in the loop
A design where a person approves or corrects what an AI system does before the result takes effect.
I
IDE
An IDE, or integrated development environment, is a code editor with running, testing, and debugging built into the same app.
Incident
An unplanned event that degrades a live service for users, from a slow page to a full outage.
Inference
Inference is the step where a trained model actually produces an answer for a new input.
Infrastructure
The layer applications run on: cloud servers, networks, and deployment systems, and the engineers who build and run it.
Infrastructure as code
Describing servers, databases, and networks in files a program applies, in place of clicking through a cloud console.
Intake meeting
The structured conversation with a hiring manager that turns a job description into a ranked, searchable set of real requirements.
Interpreted language
A language executed line by line as it runs. Python, JavaScript, Ruby, and PHP work this way.
Issue
A tracked task, bug report, or feature request filed against a repository. Project discussion on GitHub happens here.
J
Java Language
The dominant language of large-company backend systems, and the original language of Android apps.
JavaScript Language
The programming language every web browser runs. It makes web pages interactive, and it is the most used language in the world.
Job description (JD)
The document stating a role's responsibilities and requirements. The responsibilities section usually carries more truth than the requirements list.
K
L
Large language model
A large language model is a program trained on huge amounts of text to predict and generate language.
Latency
The delay between asking a system for something and getting the answer, usually measured in milliseconds.
Library
A package of prewritten code a developer pulls into a project to handle one job, like charts, payments, or sign-in.
Library author
The developer has published a reusable piece of code that other developers download and build their own projects on.
License
A license is the short legal text in a repository that says what other people may do with the code.
Llama Service
Meta’s family of open-weight language models. Anyone can download them and run them on hardware they control.
Load balancer
A service that sits in front of several servers and spreads incoming traffic among them, so no single server gets overwhelmed.
Logging
The running record a program writes about what it did, line by line. The first place developers look when something breaks.
M
Maintainer
A developer trusted to review other people's code and decide what gets accepted into a project many people rely on.
MCP (Model Context Protocol) Protocol
MCP, the Model Context Protocol, is a shared standard that lets an AI agent connect to outside tools and data.
MCP server
An MCP server is a small program that exposes a tool or a set of data to an AI agent using MCP.
Merge
Accepting a finished change into the official version of the code. Merged work is work the team accepted.
Microservices
An application split into many small services that are built and released separately, talking to each other over the network.
Mobile development
Building apps that install on phones through the App Store or Play Store, using Swift, Kotlin, or a cross-platform framework.
Model
A model is the trained program that turns an input into an output, learned from examples rather than hand-written rules.
Monitoring
Watching a live system's health through metrics, dashboards, and alerts, so the team finds problems before users report them.
Monolith
An application built, tested, and released as one piece. A normal design, and often the right one.
Monorepo
One repository holding many projects at once: several services, the website, and the shared code between them.
Must-have requirement
A skill the hire needs on day one, because the core work depends on it. Most job descriptions have three to five real ones.
N
Natural language
Natural language is ordinary human language, like English or Spanish, as opposed to code.
Next.js Framework
The most common framework for building a complete website with React, covering the pages, the links, and the server code.
Nice-to-have requirement
A skill that shortens ramp-up and that a strong hire can learn on the job, such as a specific library or a second language.
Night owl
The share of a developer's work that lands between 11pm and 4am. It carries no quality judgment.
Node.js Runtime
The program that runs JavaScript on a server. Node.js on a profile means backend work in JavaScript or TypeScript.
O
Object storage
Cloud storage for files of any size, from images to backups, fetched by name over the internet rather than from a disk.
On-call
A rotation where one developer is the designated responder if the team's live software breaks, including at night.
On-premises
Running software on servers a company owns and operates itself, in its own building or rented rack space, instead of the cloud.
Open source
Software whose code is public and free for anyone to use, read, and improve. Most of it lives on GitHub.
Open weights
A model whose trained files are published for anyone to download and run on their own hardware.
OpenAI
The AI company behind ChatGPT and the GPT models. Founded in 2015 and based in San Francisco.
Organization
A shared GitHub account owned by a company or a project team, holding the group's repositories and its members.
P
Package (dependency)
A published unit of reusable code that projects install and build on, distributed through registries like npm or PyPI.
PHP Language
The language running a large share of the existing web, including WordPress. Modern PHP work centers on the Laravel framework.
Pinned repository
Up to six repositories a developer chooses to show at the top of their GitHub profile.
Platform engineering
Building internal tools and standard paths that make a company's own engineers faster, such as one-command service deployment.
Polyglot
A developer with real authorship in several programming languages, measured from how much code they wrote in each.
Postgres Database
A free, open-source relational database. It is the default database choice for most new products and backends.
Postmortem
The written review a team produces after an incident: what broke, why, and what will prevent a repeat.
Private repository
A repository only its owner and invited people can see. Nearly all company code is private.
Product
A product is software finished to the point that people outside the team can use it, and usually pay for it.
Production
The live system real users touch. Staging is the private rehearsal copy where changes get tested first.
Programming language
The written notation developers use to give instructions to a computer, such as Python, JavaScript, or Java.
Prompt
A prompt is the text sent to a language model to tell it what to do.
Pull request
A proposed code change packaged for teammates to review, discuss, and approve before it joins the shared codebase.
Purple squirrel
Recruiting slang for a candidate who matches every requirement in a job description perfectly.
Python Language
A readable general-purpose language. It leads in data science, machine learning, backend services, and automation.
Q
R
RAG (retrieval-augmented generation) Framework
RAG, retrieval-augmented generation, is a method for looking up outside information and handing it to a model before it answers.
Rails Framework
Ruby's famous framework for building complete web products fast. GitHub and Shopify run on it.
React Library
The most widely used tool for building the screens of a website. Written in JavaScript or TypeScript, and released by Facebook.
React Native Framework
A framework for building iPhone and Android apps from one JavaScript codebase. Built on React.
README
The front-page document of a repository, explaining what the project is and how to use it.
Redis Database
An open-source database that keeps all its data in memory, which makes it extremely fast. Most often used as a cache.
Refactoring
Restructuring existing code to be cleaner and easier to change, while what it does for users stays the same.
Region
A cloud provider's group of data centers in one geographic area, such as Virginia, Frankfurt, or Tokyo.
Relational database
A database that stores data in tables with rows and columns, and links the tables to each other.
Release
A named, versioned snapshot of software made available to users, like version 2.1.0.
Repository
A project folder on GitHub holding the code plus the full history of every change ever made to it.
Rollback
Reverting a live system to the previous working version, usually within minutes. The standard first response to a bad deploy.
Ruby Language
A language designed to be pleasant to write. It is known almost entirely through Rails, the framework behind Shopify and GitHub.
Runtime
The program that actually executes code, such as Node.js running JavaScript on a server, or a browser running it on a laptop.
Rust Language
A systems language with C++ speed, where the compiler proves that the code handles memory safely. Steep to learn.
S
Scaling
Growing a system's capacity so it keeps working as users, traffic, or data multiply.
Seniority level
The scope of responsibility a developer holds: junior, mid, senior, staff, principal. Scope and ownership define it more than years.
Server
A computer that runs continuously and answers requests from other computers. All backend code lives and runs on one.
Serverless
A cloud model where the provider runs the servers. Developers upload small functions and pay only when they execute.
Shipped
The developer's work has reached real users: published releases, live demos, deployed products, or packages people install.
Side project
Software a developer builds outside work, on their own time, because they wanted it to exist.
Skill
A packaged set of instructions an agent loads when it hits a certain kind of task, so it does not have to be told twice.
SLA
A service level agreement: a written promise about uptime or speed, often with refunds or penalties if the promise breaks.
Slop
Low-effort AI output published without review. Developers use the word for prose, images, and code alike.
Snowflake Database
A data warehouse sold as a cloud service. Companies load their data in and analysts query it with SQL.
Specialist
A descriptive signal: one language carries more than 80 percent of a developer's output, showing deep single-stack focus.
Sprint
A fixed block of time, usually one or two weeks, in which a team commits to finishing a specific set of work.
SQL Language
The standard language for asking a relational database questions and changing its data. Nearly every developer touches it.
SRE
Site reliability engineer: a role focused on keeping systems online, measuring reliability, and responding to incidents.
Standup
A short daily team meeting where each developer states what they finished, what is next, and what is blocking them.
Star
A public bookmark another GitHub user gives a repository, like a favorite. Star counts measure a project's audience.
Static typing
A language feature where code declares what kind of data it handles, so tooling catches mistakes before the program runs.
Story points
A relative size estimate a team assigns to a ticket, measuring complexity and uncertainty in place of hours.
Svelte Framework
A newer tool for building the screens of a website, written in JavaScript or TypeScript. Known for small, fast results.
Swift Language
Apple's language for iPhone, iPad, and Mac apps. The core skill of iOS development.
T
Tech stack
The specific set of languages, frameworks, databases, and hosting tools a company uses to build its product.
Technical debt
The accumulated cost of past shortcuts in a codebase. It charges interest: every change in that area takes longer.
Terminal
The terminal is the window where a developer types text commands to the computer instead of clicking buttons.
Terraform Platform
The most widely used tool for infrastructure as code. It reads configuration files and builds matching cloud resources.
Test-driven
How much test code a developer writes alongside the code that runs the product.
Throughput
How much work a system completes per unit of time: requests answered, records processed, or data moved per second.
Ticket
A written unit of work in a tracking tool: one bug to fix or one feature to build, assigned to a developer.
Token
A token is a small chunk of text, close to a word or part of a word, that a model reads and writes one at a time.
Tool
Developers call almost anything they work with a tool. Some tools are apps they type in, and some are code they build with.
Topic
A label a repository owner attaches to describe what the project is about, such as machine-learning or react. GitHub search can filter by topic.
Transferable skills
Skills that carry over between technologies. Transfers run fast within a discipline and slow across disciplines.
TypeScript Language
JavaScript with type checking added. It catches many mistakes before code runs, and it is the default language of professional web teams.
U
V
Velocity
How much work a team completes per sprint, measured in its own story points. Comparable only to that team's history.
Vercel Platform
A platform that turns a GitHub repository into a live website, handling servers and deployment automatically. Maker of Next.js.
Vertical scaling
Handling more traffic by moving to a bigger, more powerful machine: more processor, more memory, more disk.
Vibe coding
Building software by describing what you want and accepting what the AI produces, without reading the code closely.
Voice agent
A voice agent is an AI agent that takes spoken audio as input and responds with spoken audio.
VS Code Platform
Microsoft’s free code editor, released in 2015. It is the most widely used editor among professional developers.
Vue Framework
A widely used tool for building the screens of a website, written in JavaScript or TypeScript. React's closest peer.
W
Watch
Following a repository so GitHub sends updates about it. Watching takes one click and requires writing no code.
Web app
An application that runs in the browser with nothing to install, like Gmail or Figma. The default form of modern software.
Wrapper
A product built on top of a model someone else trained. Used as a plain description and as an insult.