In my repo, I have one branch (branch_1) and from it, I have been committing some changes. Then I created a new branch from branch_1, branch_2.
Master---
\
Branch_1--commit1--commit2
\
Branch_2 (current branch)
Meanwhile, a review was done in Branch_1 and I made some changes:
Master---
\
Branch1--squashed commit1,commit2--commit3--commit4
\
Branch2 (current branch)
How can I now apply the last changes of branch_1 in branch_2? What it means to merge branch_1 onto branch_2 and vice versa.
Technically speaking, what you're asking for is a rebase (which is laymens terms means moving the point where you branch off around on the trunk), a merge is a superset of it.
However, merging Branch1 into the current branch (Branch2) will do what you want.
What it means to merge branch_1 onto branch_2 and vice versa.
It means bringing in all the changes from one branch into another. The order is important, it is what determines what branch you're writing into.