Before we go anywhere near the internals, let’s build a rock-solid definition in plain English.

The Simple Definition

git push is a command that uploads the commits you’ve made on your local machine to a remote repository, so that other people (or other machines, like a deployment server) can see and use your changes. A “commit” is simply a saved snapshot of your project at a specific point in time — think of it as a save file in a video game. Git tracks a whole chain of these save files, and git push is the mechanism that copies the new ones in that chain to a shared location.

Why This Command Exists

Git was designed to be a “distributed” version control system, which means every single developer has a full, independent copy of the entire project history on their own machine — not just the latest files, but every past version too. This is powerful because you can work completely offline: you can save progress, undo mistakes, and branch off into experiments without ever touching the internet. But it creates an obvious problem: if everyone’s copy lives in isolation, how does anyone ever combine their work? git push (and its counterpart, git pull) are the bridges that connect these isolated copies back together.

To understand what gets pushed, we first need to understand where things live before and after the push.

Every developer on a team has their own local repository, and all of those local repositories synchronize through one shared remote repository. This “hub and spoke” pattern means you never talk directly to a teammate’s laptop — you always go through the central remote. git push is one half of that synchronization: it sends your new commits up to the hub. git pull is the other half: it brings other people’s commits down from the hub into your own local copy.

graph LR
    A[Alice's Laptop
Local Repository] -- git push --> R[(Remote Repository
e.g. GitHub)]
    B[Bob's Laptop
Local Repository] -- git push --> R
    R -- git pull --> A
    R -- git pull --> B
        

Now let’s open the hood and see exactly what happens, step by step, when you type this command and hit enter.

sequenceDiagram
    participant L as Local Repository
    participant R as Remote Repository (origin)
    L->>L: Compare local main vs origin/main
    L->>L: Package new commit objects
    L->>R: Upload packaged objects
    R->>R: Unpack and store objects
    R->>R: Move main pointer to new commit
    R-->>L: Confirm success
    L->>L: Update local origin/main bookmark
        

git push always operates on branches, so understanding branches is essential to understanding push.

A branch is best understood as a movable sticky note attached to one commit in your project’s history. When you make a new commit while “on” a branch, Git simply slides that sticky note forward to point at the newest commit. When you run a plain git push, you are telling Git: “take whatever commit my current branch’s sticky note is pointing at, and move the matching sticky note on the remote to point at the same place.” Only the branch you’re currently on (and any commits it depends on) is affected — your other branches stay exactly where they were.

Tracking Relationships

The first time you push a brand-new local branch, Git doesn’t automatically know which remote branch it should update — you typically tell it once, and from then on the two branches are “linked” as a tracking pair. After that link exists, a plain git push with no extra arguments knows exactly where to send your work, because it remembers the relationship you set up.

This is the single most common source of confusion for beginners: why does git push sometimes just work, and other times get rejected?

The Fast-Forward Case (Success)

If the remote branch hasn’t moved at all since your local machine last checked in — meaning nobody else has pushed anything new — your new commits simply build directly on top of what the remote already has. Git can move the remote’s pointer forward in a straight line, like extending a train track. This is called a “fast-forward,” and it’s the smooth, no-conflict scenario.

The Non-Fast-Forward Case (Rejected)

If a teammate pushed their own commits to the same branch after you last synced, the remote’s history has now branched away from what your local machine expects. Git refuses to blindly overwrite that history, because doing so would silently erase your teammate’s work. Instead, it rejects the push and asks you to first bring down the missing commits (usually with git pull), reconcile the two histories on your own machine, and then push the combined result.

graph TD
    subgraph "Fast-Forward (allowed)"
    A1[Remote: C1 - C2] --> A2[Local adds C3] --> A3[Remote becomes: C1 - C2 - C3]
    end
    subgraph "Non-Fast-Forward (rejected)"
    B1[Remote: C1 - C2 - C4 by teammate] 
    B2[Local still expects: C1 - C2 - C3]
    B1 -.conflict.- B2
    end
        

git push accepts several options that change its default behavior. Here are the ones you’ll run into constantly, described conceptually.

These three commands are the ones beginners mix up most often. Here’s how they actually differ.

A useful way to remember this: git push is the only one of the three that sends information outward. The other two are both about bringing information inward, and they differ only in whether that new information is immediately blended into your working copy or simply stored on the side for you to review first.

Like every tool, git push brings real benefits alongside a few sharp edges worth knowing about.

Since git push is the gateway from your machine to a shared server, it naturally touches on a few security concerns.

A short, practical checklist that separates smooth teams from ones constantly fighting their own Git history.

git push isn’t just an academic concept — it sits at the center of how modern software actually gets built and shipped.

No. Git is smart enough to calculate the difference between what the remote already has and what’s new on your machine, and only that difference is uploaded.

The push simply fails and the remote repository is left unchanged, because Git only finalizes the branch pointer move after all the data has arrived successfully. You can safely try again once you’re back online.

You can push a new commit that reverses the change, or in some cases force push over it, but you should treat a successful push as something others may have already seen, downloaded, or built upon.

No — “saving” your work locally happens when you make a commit. Pushing is the separate, later step of sharing those already-saved commits with a remote repository.

Because your brand-new branch didn’t yet have a matching branch on the remote to link to, so Git needed you to confirm where it should create one and track it going forward.

git push is the command that turns your private, local commits into shared, visible history on a remote repository. Under the hood, it compares your branch against the remote’s last known position, packages up only the new objects, uploads them, and then moves the remote’s branch pointer forward to match. Understanding this mechanism — rather than memorizing the command as a magic incantation — is what turns confusing rejected pushes and force-push accidents into predictable, manageable events.