3 types of branches:

1. local branches (stored locally) (e.g. main)

2. remote branches (stored at remote) (e.g. main)

3. local copies of remote branches (stored at locally) (e.g. origin/main)

For example, if at the remote, we have main branch and x branch, then locally, along with local main branch and local x branch, we also have origin/main branch and origin/x branch.

These branches (type 3) get updated at the time of pulling/pushing only and they convey the info. about latest commits pushed/pulled.

Suppose that currently the local main branch and remote main branch are at sync.

Now, consider 3 cases:

Case 1: We make a commit on local main branch.

In this case, the local main branch gets updated to point to the new commit.

But, neither the local origin/main branch nor the remote main branch gets updated.

However, when we push the main branch to origin, both the local origin/main branch and the remote main branch gets updated to point to the new commit.

Case 2: The remote main branch gets a new commit.

In this case, the remote main branch gets updated to point to new commit.

But, neither the local main branch nor the local origin/main branch gets updated.

However, when we pull the main branch from origin, both the local main branch and the local origin/main branch gets updated to point to the new commit.

Case 3: We make a commit (say c1) on local main branch and we also make some other commit (say c2) on remote main branch.

In this case, the local main branch gets updated to point to commit c1, the remote main branch gets updated to point to commit c2.

But, local origin/main branch doesn't get updated.

Now, pushing or pulling require merging. It may cause merge conflicts which may be needed to be resolved.

Hence, it is safer to use git fetch here.

First use [git fetch origin] command which will just update local copy of remote branch (i.e. origin/main). This means that local origin/main branch will point to commit c2.

Now, the local main branch will point to commit c1, the local origin/main branch to commit c2, and the remote main branch to commit c2.

Now, we require to merge local origin/main branch into local main branch.

We can run merge command to merge here.

Note that we could also run git pull command instead of fetch then merge, since fetching + merging is equivalent to pulling, but then if any merge conflicts arise, then we need to resolve the conflicts as well.

git pull origin main = git fetch origin + git merge main origin/main

Now, our local main branch is pointing to merged commit (say c3) and local origin/main branch and remote main branch are pointing to commit c2.

Now, we can push the main branch which will update both the local origin/main branch and remote main branch to point to commit c3.

Now, all the 3 branches (local main, local origin/main and remote main branch) are at sync with each other.