What is Git?

Git is a version control system: it tracks changes to files over time so you can revert, compare, and collaborate. Every commit is a snapshot of your project at a point in time.

Without version control, you're stuck with "final.doc" and "final_v2.doc." With Git, you have a full history, branches for experiments, and the ability to merge work from others.

A commit saves a snapshot with a message. The working directory is your files; staging (git add) selects what goes into the next commit; the repository stores all commits.

Branches let you work on features or fixes without touching the main line. Merge (or rebase) brings branch changes back into another branch. main (or master) is usually the default branch.

Understanding commit/branch/merge is enough to use Git daily and to understand how pull requests and CI/CD pipelines work.

A remote is a copy of the repo elsewhere (e.g. GitHub, GitLab). clone copies a remote to your machine; pull fetches and merges updates; push sends your commits to the remote.

origin is the default name for the remote you cloned from. fetch downloads new commits without merging; pull = fetch + merge.

Remotes enable collaboration: everyone pushes to the same repo, and pull requests (or merge requests) propose merging a branch after review.

Feature branch: create a branch (e.g. feature/login), commit, push, open a pull request (PR) to merge into main. Review and merge.

Trunk-based: short-lived branches, frequent merges to main. Git flow uses long-lived develop and release branches. Most teams use something in between.

Rebase vs merge: merge creates a merge commit; rebase replays your commits on top of another branch for a linear history. Both are valid; teams choose one style.

Merge combines two branches with a merge commit. History shows when branches came together. Rebase takes your branch's commits and replays them on top of another branch (e.g. main). Result: a linear history as if you had started from the latest main. Use rebase to keep a clean history; never rebase commits already pushed if others use that branch.

Stash (git stash) temporarily saves uncommitted changes so you can switch branches or pull without committing. git stash pop brings them back. Revert (git revert <commit>) creates a new commit that undoes a previous one-safe for shared history. Cherry-pick (git cherry-pick <commit>) applies one specific commit from another branch onto your current branch.

Conflicts happen when two branches change the same lines. Git marks conflict regions in the file; you edit, resolve, then git add and git commit (merge) or git rebase --continue (rebase).

Merge vs rebase

Git is the input to CI/CD: pipelines run on every push or PR. Understanding branches and commits helps you design workflows and fix broken builds.

Cloud and DevOps: infrastructure as code (Terraform, Ansible) lives in Git. GitOps uses Git as the source of truth for deployments.

Every role-developer, DevOps, SRE-benefits from confident Git use: small commits, clear messages, and knowing how to undo mistakes.