Git is a distributed version control system designed to track changes in source code during software development. It enables multiple people to work on a project simultaneously without overwriting each other's work and helps manage the evolution of the codebase over time.

Key Purposes of Git

1. Version Control:

   • Git tracks changes to files in a repository. Each change is recorded as a commit, which includes a snapshot of the files and a description of the change.
   • This allows developers to revert to previous versions of the code, compare different versions, and understand the history of changes.

2. Collaboration:

   • Git allows multiple developers to work on the same project simultaneously. Changes from different developers can be merged together, enabling collaborative development.
   • Developers can work on separate branches (independent lines of development) and merge their changes into the main branch when they are ready.

3. Branching and Merging:

   • Branching: Git allows developers to create branches for new features, bug fixes, or experiments. Each branch can be developed independently from the main codebase.
   • Merging: Changes made in branches can be merged back into the main branch or other branches, integrating the new work with the existing code.

4. Tracking Changes:

   • Git keeps a history of changes to files, including who made the changes and when. This history is invaluable for debugging and understanding how the project has evolved.
   • Each commit includes metadata such as the author, date, and commit message.

5. Backup and Recovery:

   • Git stores the entire history of changes in the repository, which acts as a backup of the codebase. If something goes wrong, you can recover previous versions of files or the entire project.

6. Code Review and Quality Control:

   • Git facilitates code reviews by allowing developers to compare changes, discuss code, and ensure that new code meets quality standards before it is merged into the main branch.
   • Tools integrated with Git, such as GitHub or GitLab, provide platforms for pull requests and code reviews.

7. Distributed Development:

   • Unlike centralized version control systems, Git is distributed. Each developer has a full copy of the repository, including its history. This means that work can continue even if the central server is down.
   • Changes are shared between repositories through pushes and pulls, enabling collaboration across different locations.

Basic Concepts and Commands

1. Repository (Repo):

   • A Git repository is a directory that contains your project files and the history of changes made to them. Repositories can be local (on your computer) or remote (hosted on a server like GitHub).

2. Commit:

   • A commit is a snapshot of the changes made to files in the repository. Each commit has a unique identifier and includes a commit message describing the changes.

   git commit -m "Commit message describing the changes"
   

3. Branch:

   • A branch is a separate line of development. The default branch is usually called main or master.

   git branch new-branch  # Create a new branch
   git checkout new-branch  # Switch to the new branch
   

4. Merge:

   • Merging integrates changes from one branch into another.

   git merge branch-name  # Merge changes from "branch-name" into the current branch
   

5. Clone:

   • Cloning creates a copy of a remote repository on your local machine.

   git clone https://github.com/user/repo.git  # Clone a repository from a remote server
   

6. Push and Pull:

   • Push: Sends local changes to a remote repository.

     git push origin branch-name  # Push changes to the remote repository
     

   • Pull: Retrieves changes from a remote repository and merges them into the local branch.

     git pull origin branch-name  # Pull changes from the remote repository
     

7. Status:

   • Shows the status of the working directory and staging area, including uncommitted changes.

   git status
   

8. Log:

   • Displays the commit history for the repository.

   git log
   

Summary

Git is a powerful tool for managing and tracking changes in source code during software development. It supports collaborative work, maintains a detailed history of changes, and facilitates branching and merging. By using Git, developers can efficiently manage their codebase, collaborate with others, and maintain a reliable record of the project's evolution.