Git Version Control Basics: What is a Commit Hash? Why is It Important?

In Git, each commit generates a unique 40-character hexadecimal string called the commit hash, which serves as the "ID number" for the commit. It is generated by hashing the commit content (files, messages, timestamps, etc.) using a hash algorithm, and remains unchanged if the content remains identical. The significance of commit hash lies in four aspects: First, it uniquely identifies versions, facilitating the location of historical commits via `git log`. Second, it is the core for version rollbacks (`git checkout`/`revert`) and branch management, enabling the recognition of commit order. Third, it distinguishes modifications from different developers during collaboration to avoid confusion. Fourth, it is tamper-proof, acting as an "anchor" for historical records. For practical use, it is sufficient to remember the first 7 characters daily. These can be viewed through `git log` and used to operate commands like `git checkout`, `revert`, and `branch`. As a cornerstone of Git version control, commit hash ensures clearer historical tracking, rollbacks, and collaboration. **Core**: A unique 40-character hexadecimal string generated from commit content, critical for version management, collaboration, and rollbacks.