What is Git? History, Linus Torvalds, and Git vs Other VCS Tools
Git is the most widely used version control system in the world today, powering everything from tiny personal projects to the Linux kernel itself — the very project that inspired its creation. Understanding where Git came from, why it was built the way it is, and how it differs from the tools it replaced gives you a much deeper appreciation for the commands you'll learn in the rest of this module.
Learning Objectives
- Define Git and its role as a distributed version control system.
- Recount the history of Git's creation by Linus Torvalds in 2005.
- Explain why the BitKeeper licensing dispute led to Git's creation.
- Compare Git's design goals and speed against other VCS tools.
Key Terms to Know Before Learning what is git
- Git: A free, open-source, distributed version control system designed to handle projects of any size with speed and integrity of data.
- Linus Torvalds: The Finnish-American software engineer who created the Linux kernel in 1991 and later created Git in 2005.
- BitKeeper: A proprietary distributed version control system the Linux kernel project used before Git, whose licensing terms were revoked in 2005, prompting Torvalds to build a replacement.
- Repository (repo): A storage location, managed by Git, that holds a project's files along with the complete history of changes made to them.
- Data integrity: Git's design principle of using cryptographic hashing (SHA-1/SHA-256) to ensure stored history cannot be silently corrupted or altered without detection.
How what is git Actually Works
Git's origin story is unusually well documented because it's tied directly to one of the most famous projects in computing history: the Linux kernel. Through the early 2000s, the Linux kernel development team — thousands of contributors worldwide — used a proprietary distributed version control system called BitKeeper, made available for free to the open-source community by its company, BitMover.
In 2005, a dispute arose after a developer reverse-engineered parts of BitKeeper's protocol, and BitMover revoked free access to the tool. The Linux kernel project needed a new version control system immediately — and needed it to handle the scale and speed that thousands of distributed contributors around the world required. Linus Torvalds, the creator of Linux itself, decided to write a new version control system from scratch. In roughly ten days, he produced the first working version of what would become Git.
Torvalds designed Git with a small number of explicit goals: speed, simplicity, strong support for non-linear development (thousands of parallel branches), being fully distributed, and being able to handle huge projects like the Linux kernel efficiently. He was also deeply focused on data integrity — Git identifies every commit, file, and change with a cryptographic hash, so any corruption or tampering in the history is immediately detectable.
Git differs from earlier tools like SVN or CVS not just in being distributed (see Lesson 2), but in a few other key ways:
- **Snapshots, not diffs**: Most older VCS tools store data as a list of file-based changes (deltas) over time. Git instead thinks of its data as a series of snapshots of the entire project's file tree at each commit — if a file hasn't changed, Git just stores a reference to the previous identical file rather than storing it again.
- **Nearly everything is local**: Because of its distributed nature, most Git operations (viewing history, comparing versions, committing) require no network access at all, making it extremely fast.
- **Branching is lightweight**: Creating a branch in Git is nearly instantaneous, encouraging a workflow where developers create many small, disposable branches for experiments and features — something that was cumbersome in centralized tools.
Git's open-source nature, combined with the massive success of platforms like GitHub (launched in 2008), cemented it as the default choice for version control across the industry, far surpassing tools like Mercurial, SVN, and Perforce in overall adoption today.
what is git: Visual Walkthrough
Draw a simple timeline from 1991 to today. Mark 1991: 'Linus Torvalds creates Linux'. Mark early-2000s: 'Linux kernel uses BitKeeper (proprietary DVCS)'. Mark 2005: 'BitKeeper license revoked — Torvalds builds Git in ~10 days'. Mark 2008: 'GitHub launches, accelerating Git adoption'. Mark Today: 'Git is the dominant VCS worldwide'.
what is git: Quick Reference Table
| Aspect | Git | SVN | Mercurial |
|---|---|---|---|
| Architecture | Distributed | Centralized | Distributed |
| Data model | Snapshots of full tree | File-based deltas | Snapshots (similar to Git) |
| Branching cost | Nearly instant, lightweight | Slow, server-dependent | Fast, but less flexible than Git |
| Created by | Linus Torvalds (2005) | CollabNet (2000) | Matt Mackall (2005) |
| Industry adoption | Dominant (GitHub, GitLab) | Niche / legacy systems | Used by some large orgs (e.g., historically Meta) |
what is git: Command Syntax and Examples
# Checking your installed Git version
git --version
# Viewing the built-in help documentation for Git or any command
git help
git help commit
# A first glance at Git's snapshot model — every commit is a full snapshot reference
git log --oneline
# Example output:
# a1b2c3d Add login page
# 9f8e7d6 Fix navbar alignment
# 3c4d5e6 Initial commitBreaking Down the what is git Example
Running `git --version` confirms Git is installed correctly (covered in depth in the next lesson). `git help` opens Git's extensive built-in documentation, which is useful since Git has hundreds of commands and options. The `git log --oneline` output previews Git's snapshot model: each line represents one committed snapshot, identified by a unique short hash, rather than a simple line-based diff — a direct result of the data-integrity design goals Torvalds built into Git from day one.
How what is git Is Used on Real Engineering Teams
- The Linux kernel — the very project that inspired Git's creation — is still managed with Git today, with tens of thousands of contributors worldwide submitting changes.
- GitHub, built entirely around Git, hosts well over 100 million repositories and is the default collaboration platform for open-source and enterprise software alike.
- Companies like Microsoft (which acquired GitHub in 2018) and Google use Git extensively, often building custom tooling on top of it to handle enormous monorepos.
- Nearly every modern programming bootcamp, computer science curriculum, and technical hiring interview assumes baseline Git fluency as a core professional skill.
what is git Interview Questions and Answers
Q1. Who created Git and why?
Git was created by Linus Torvalds, the creator of the Linux kernel, in 2005. He built it after the Linux kernel project lost free access to its previous version control tool, BitKeeper, due to a licensing dispute. Torvalds wrote Git in about ten days to meet the kernel project's need for a fast, distributed system capable of handling thousands of contributors.
Q2. How does Git's data model differ from older version control systems?
Older systems like SVN and CVS typically store data as a series of file-based changes (deltas) over time. Git instead stores data as a series of snapshots of the entire project at each commit; if a file hasn't changed between commits, Git just links to the previously stored identical version rather than storing a new delta.
Q3. Why is Git described as prioritizing data integrity?
Every object in Git — files, trees, and commits — is identified by a SHA hash calculated from its content. This means it's cryptographically impossible to change a file's content without changing its hash, so any corruption or tampering anywhere in the project's history can be immediately detected.
what is git Quiz: Test Your Understanding
1. Who created Git and in what year?
- Bill Gates, 1998
- Linus Torvalds, 2005
- Guido van Rossum, 2001
- Mark Zuckerberg, 2008
Answer: B. Linus Torvalds, 2005
Explanation: Linus Torvalds, the creator of the Linux kernel, wrote Git in 2005 after the Linux project lost access to its previous VCS, BitKeeper.
2. What event directly led to the creation of Git?
- The invention of GitHub
- A licensing dispute over BitKeeper
- The release of the first Macintosh computer
- A security vulnerability in SVN
Answer: B. A licensing dispute over BitKeeper
Explanation: The free license for BitKeeper, the proprietary DVCS the Linux kernel team was using, was revoked in 2005, prompting Torvalds to quickly build Git as a replacement.
3. How does Git primarily store project history?
- As a single compressed file
- As a series of full-project snapshots
- As a list of line-by-line diffs only
- As images of each file
Answer: B. As a series of full-project snapshots
Explanation: Git conceptually stores a snapshot of the entire project tree at each commit, reusing unchanged file content rather than storing incremental diffs the way older systems did.
what is git: Common Mistakes Beginners Make
- Confusing Git with GitHub — Git is the version control tool; GitHub is a company/platform that hosts Git repositories online and adds collaboration features on top.
- Assuming Git and Linux are the same project — Git was created to manage the Linux kernel's source code, but it is an entirely separate, general-purpose tool usable for any project.
- Thinking Git stores only line-by-line differences like older tools — Git's model is based on snapshots of the full project tree at each commit.
what is git: Exam-Ready Quick Notes
- Git was created by Linus Torvalds in 2005, in response to the BitKeeper licensing dispute.
- Git is a distributed version control system, unlike SVN's centralized model.
- Key design goals: speed, data integrity (via SHA hashing), support for non-linear (branching) development.
what is git: Key Takeaways
- Git was born out of necessity — the Linux kernel project needed a fast, distributed replacement for BitKeeper almost overnight.
- Git's snapshot-based data model and cryptographic hashing set it apart from older delta-based systems like SVN.
- Git's design priorities — speed, integrity, and lightweight branching — directly explain the behavior of the commands you'll learn next.
Frequently Asked Questions About what is git
Q1. What is Git in simple terms?
Git is a tool that tracks changes to files over time, allowing multiple people to collaborate on a project, see its full history, and revert to earlier versions — all without needing constant access to a central server.
Q2. Is Git the same as GitHub?
No. Git is the underlying version control software that runs on your computer. GitHub is a separate company and website that hosts Git repositories online and adds features like pull requests, issue tracking, and team collaboration on top of Git.
Q3. Why did Linus Torvalds create Git?
The Linux kernel project was using a proprietary tool called BitKeeper, whose free license was revoked in 2005 after a licensing dispute. Torvalds needed a fast, distributed replacement immediately and built Git himself in about ten days.
Q4. Is Git free to use?
Yes, Git is free and open-source software, licensed under the GNU General Public License (GPL), meaning anyone can use, study, and modify it.
Q5. What makes Git different from tools like SVN?
Git is distributed (every clone has the full project history) rather than centralized (all history lives on one server), stores snapshots of the full project rather than line-based diffs, and supports extremely fast, lightweight branching.
Summary
Git is a free, open-source, distributed version control system created by Linus Torvalds in 2005 after the Linux kernel project lost access to its previous tool, BitKeeper, due to a licensing dispute. Git was designed for speed, strong data integrity through cryptographic hashing, and lightweight, non-linear branching — differing from older centralized tools like SVN, which store changes as file-based deltas on a single server. Git's open-source nature and the rise of GitHub cemented it as the dominant version control system used across the software industry today.