Software Development Vocabulary in English

Version-control is a system that tracks every change made to a codebase over time. The most widely used version-control system today is Git. With version-control, developers can see exactly what changed, who changed it, and why — through commit messages. If a bug is introduced, the team can roll back to a previous working version. Version-control also enables collaboration: multiple developers can work on different branches simultaneously without overwriting each other’s work. Platforms like GitHub, GitLab, and Bitbucket host repositories and add tools for code review, issue tracking, and CI/CD pipelines on top of Git.

A pull-request (often called a PR or merge request) is a formal proposal to merge code from one branch into another. When a developer finishes a feature or fix on their branch, they open a pull-request on platforms like GitHub. This triggers an automated CI/CD pipeline that runs tests, and it notifies teammates to review the code. Reviewers read through the changes, leave comments, request improvements, or approve the PR. Once it has enough approvals and all tests pass, the code is merged. The code-review process is essential for catching bugs, sharing knowledge, and maintaining consistent code quality across a team.

CI/CD stands for Continuous Integration and Continuous Deployment (or Delivery). Continuous Integration means that every time a developer pushes code, automated tests run immediately to check that nothing is broken. Continuous Deployment means that if all tests pass, the code is automatically deployed to a live environment with no manual steps. Together, CI/CD pipelines make software delivery faster and more reliable by removing manual bottlenecks and catching errors early. Tools commonly used for CI/CD include GitHub Actions, GitLab CI, Jenkins, and CircleCI. Understanding CI/CD is essential for any developer working on a professional team today.

A repository is the entire storage container for a project — it holds all the code, all the history of every change ever made, and all the branches. A branch is a named pointer to a particular line of development within that repository. You can think of a repository as a tree and branches as the individual branches growing from the trunk. The “main” or “master” branch usually represents the stable, production-ready code, while feature branches allow developers to work on new functionality safely before merging it back in.

Refactoring is the disciplined process of restructuring existing code to make it cleaner, more readable, and easier to maintain — without changing what the code actually does for the user. Developers refactor when code has become too complex, when functions are too long, when similar logic is duplicated in multiple places, or when names are unclear. Good refactoring is always backed by tests so you can verify that behaviour has not changed. Teams often schedule dedicated refactoring time after delivering a new feature, sometimes called a “clean-up sprint” or “technical debt reduction” phase.

An API (Application Programming Interface) is a defined set of rules and endpoints that allows one piece of software to communicate with another. For example, a weather app on your phone uses an API to request current temperature data from a remote weather service. In web development, REST APIs and GraphQL APIs are most common. APIs use HTTP requests — GET (retrieve data), POST (send data), PUT (update data), and DELETE (remove data). Understanding APIs is fundamental for any developer, because modern applications almost always depend on multiple external APIs for authentication, payments, maps, data, and more.

Testing means writing and running automated checks — unit tests, integration tests, end-to-end tests — to verify that the code behaves as expected before it reaches users. Debugging is what happens when something goes wrong: you investigate the cause of an error, reproduce it, and fix it. The two are complementary — good tests help you catch bugs early, and debugging skills help you understand and fix the bugs that slip through. Documentation is written material that explains what the code does, how to use it, and how to set it up. All three practices are essential for maintaining a healthy, professional codebase.

A sprint is a short, fixed period — typically one or two weeks — during which a software team plans and completes a set of specific tasks selected from a product backlog. Sprints are a core part of the Scrum agile framework. At the start of each sprint, the team holds a planning meeting to decide what they will work on. During the sprint, they hold daily stand-up meetings to share progress and raise blockers. At the end, a sprint review shows stakeholders what was completed, and a retrospective reflects on what went well and what to improve. Sprints help teams deliver value continuously rather than waiting for a large release.

Scalability refers to a software system’s ability to handle an increasing amount of load — more users, more data, or more requests — without becoming slow or unreliable. A system that works well for 100 users but crashes with 10,000 users is not scalable. Developers achieve scalability through techniques such as horizontal scaling (adding more servers), caching (storing frequently requested data so it does not need to be recalculated), database optimisation, and load balancing (distributing traffic across multiple servers). Scalability is particularly important for consumer-facing applications that may experience sudden spikes in traffic.

A monolith is a single, large application where all components — user interface, business logic, and database access — are tightly coupled and deployed together. Microservices architecture breaks a large application into many small, independent services, each responsible for a specific business function (for example: authentication, payments, or notifications). Each microservice communicates with others via APIs and can be developed, deployed, and scaled independently. While microservices offer flexibility and resilience, they also introduce complexity around communication, monitoring, and distributed system failures. Most large technology companies, such as Netflix and Amazon, use microservices architectures to manage their platforms at scale.