Version Control Systems

A Version Control System (VCS) is a tool used in software development and collaborative projects to track and manage changes to source code, documents, and other files. Whether you are working alone or in a team, version control helps ensure your work is safe, organized, and easy to collaborate on. It allows developers to:

• Record and track every update to the codebase
• Collaborate on code without overwriting each other's work
• Revert to earlier states of the project if needed
• Maintain a detailed and structured history of the project’s evolution

If something breaks or doesn’t work, the team can compare versions, isolate the issue, and restore stable code without starting from scratch.

Types of Version Control Systems

There are three main types of Version Control Systems:

1. Local Version Control Systems (Local VCS)

A Local Version Control System operates entirely on your personal machine without any connection to a remote repository. All changes and version history are stored in a local database on your computer.

In this setup, you are the only contributor, and there is no collaboration or sharing of changes with other users. Each developer maintains their own isolated repository.

Key Characteristics

• No internet or server dependency.
• Useful for individual projects.
• Limited to single-user environments.

2. Centralized Version Control Systems

In a Centralized Version Control System, all the files and their version history are stored in a single central server. This server acts as the main source for the entire project. Developers connect to this server to access or modify files but they do not maintain a full local copy of the project, instead they work with the most recent versions pulled from the server.

Two things are required to make your changes visible to others

• You commit
• They update

Whenever a developer wants to make changes, they check out the required files from the server. Once the work is done, they commit their changes back to the central repository. Other developers can then update their local versions to see those changes.

• The benefit of CVCS (Centralized Version Control Systems) is that it makes collaboration among developers while providing insight into what everyone else is doing on the project.
• It allows administrators to have fine-grained control over who can do what. It has some downsides as well which led to the development of DVCS.
• The most obvious drawback is the single point of failure represented by the centralized repository. If the repository goes down, you would not be able to collaborate or save changes.

3. Distributed Version Control Systems

Distributed version control systems contain multiple repositories. Each user has their own repository and working copy. Just committing your changes will not give others access to your changes. This is because commit will reflect those changes in your local repository and you need to push them in order to make them visible on the central repository.

Similarly, When you update, you do not get others changes unless you have first pulled those changes into your repository. 

To make your changes visible to others, 4 things are required:  

• You commit
• You push
• They pull
• They update

The most popular distributed version control systems are Git and Mercurial. They help us overcome the problem of single point of failure.  

Top 5 Free Version Control Systems

Below are five most widely used free VCS tools, perfect for individuals and teams. Each of these version control systems serves different needs, and the choice depends on the project size, team collaboration style and workflow preferences.

1. Git

Git is the most widely used Distributed Version Control System, developed by Linus Torvalds in 2005 for managing the Linux kernel. It is highly efficient, supports branching and merging, and has a fast, decentralized workflow. Git is the backbone of services like GitHub, GitLab and Bitbucket, making it a popular choice for developers worldwide.

Key Features of Git

• Lightweight, fast and efficient.
• Branching and merging are simple and non-destructive.
• Provides powerful commands like git clone, git pull and git push.

2. Subversion (SVN)

Subversion is a popular centralized version control system. While it is not as commonly used in open-source projects today, SVN is still widely used by many organizations and enterprises for its simplicity and centralized structure.

Key Features of SVN

• Single central repository.
• Supports branching and tagging but it is less flexible than Git.
• Versioning of files and directories.

3. Mercurial

Mercurial is another distributed version control system similar to Git but with a simpler interface. It is well-suited for both small and large projects and is used by companies like Facebook and Mozilla.

Key Features of Mercurial

• Simple, fast and scalable.
• Supports branching and merging.
• Includes tools for managing project history and changes.

4. CVS (Concurrent Versions System)

CVS is one of the earliest and most influential centralized version control systems. It was widely adopted in the late 1990s and early 2000s and helped shape how modern VCS tools operate. Though largely outdated today, CVS laid the foundation for later tools like Subversion and Git.

Key Features of CVS

• Centralized repository architecture
• Tracks changes to individual files over time
• Allows multiple developers to work on the same codebase
• Basic support for branching and tagging, though more limited than modern alternatives.

5. Bazaar

Bazaar is a distributed version control system developed by Canonical, the creators of Ubuntu. Unlike Git or Mercurial, Bazaar supports both centralized and distributed workflows, making it a flexible choice for teams with varied needs. Although it's no longer actively developed, Bazaar was once used by major projects like Ubuntu and MySQL.

Key Features of Bazaar

• Supports both centralized and distributed version control models
• Easy to learn and beginner-friendly
• Human-readable command structure (e.g., bzr commit, bzr push)
• Cross-platform compatibility (Linux, Windows, macOS)

Version control systems are vital for modern software development, enabling teams or solo developers to track changes, collaborate efficiently, and maintain stable, testable code. Among various types, distributed systems like Git are the most popular, offering flexibility, powerful features, and seamless collaboration.