Git is a “content tracker” – it records how files change over time. Think of it as a detailed history of your project, noting when, where, and by whom changes were made. This enables key features like:
- Tracking who owns specific changes.
- Backing up and reverting to older versions.
- Synchronizing changes across multiple locations.
Git’s underlying structure is a Directed Acyclic Graph (DAG) of Hashes. Each “hash” represents a specific version (or “commit”) of your content.
Understanding the Directed Acyclic Graph (DAG)
A DAG shows the relationships between different versions of your content. It’s like a family tree for your files:
+-------+ +-------+ +-------+
| grand |------>|parent |------>| child |
| parent| | | | |
+-------+ +-------+ +-------+
- Directed: Changes flow from a version to its parent.
- Acyclic: There are no loops – a version doesn’t directly influence itself.
Hashes and Cryptographic Security
The DAG is built using “hashes”. A hash function takes any size input and produces a fixed-size output. In Git, each piece of content is hashed, creating a unique fingerprint. Cryptographic hashes, like SHA-1 (used in older versions) and SHA-256, are particularly important because they are designed to be extremely difficult to reverse – meaning you can’t figure out the original content just from its hash.
Commits: Snapshots of Content
A “commit” is a snapshot of your content at a specific point in time. Even though Git tracks changes at a file level, the commit itself records all the details of those alterations. We’ll delve deeper into commits in the next section.