What is the intended use-case for git stash?

If I work on branch A and suddenly need to work on branch B before being ready with a commit on branch A, I stash my changes on A, checkout B, do my work there, then checkout A and apply the stash.

If I work on A and I want to stop working for the day, should I stash my work and then apply it the next day (when I resume my work), or should I just leave things as they are—uncommitted modified files in the working directory? I don't see why I would need to use stash in this case, except if there is some security benefit.

Also, another scenario: I work both at work and at home. If I am not ready with a commit when I want to go home, can I stash my work, push it to GitHub and then pull that stash at home?

Stash is just a convenience method. Since branches are so cheap and easy to manage in git, I personally almost always prefer creating a new temporary branch than stashing, but it's a matter of taste mostly.

The one place I do like stashing is if I discover I forgot something in my last commit and have already started working on the next one in the same branch:

# Assume the latest commit was already done
# start working on the next patch, and discovered I was missing something

# stash away the current mess I made
git stash save

# some changes in the working dir

# and now add them to the last commit:
git add -u
git commit --amend

# back to work!
git stash pop

I will break answer on three paragraphs.

Part 1:

git stash (To save your un-committed changes in a "stash". Note: this removes changes from working tree!)

git checkout some_branch (change to intended branch -- in this case some_branch)

git stash list (list stashes)

You can see:
stash@{0}: WIP on {branch_name}: {SHA-1 of last commit} {last commit of you branch}
stash@{1}: WIP on master: 085b095c6 modification for test

git stash apply (to apply stash to working tree in current branch)

git stash apply stash@{12} (if you will have many stashes you can choose what stash will apply -- in this case we apply stash 12)

git stash drop stash@{0} (to remove from stash list -- in this case stash 0)

git stash pop stash@{1} (to apply selected stash and drop it from stash list)

Part 2:
You can hide your changes with this command but it is not necessary.
You can continue on the next day without stash.
This commands for hide your changes and work on different branches or for implementation some realization of your code and save in stashes without branches and commit your custom case!
And later you can use some of stashes and check which is better.

Part 3:
Stash command for local hide your changes.
If you want work remotely you must commit and push.

The main idea is

Stash the changes in a dirty working directory away

So Basicallly Stash command keep your some changes that you don't need them or want them at the moment; but you may need them.

Use git stash when you want to record the current state of the working directory and the index, but want to go back to a clean working directory. The command saves your local modifications away and reverts the working directory to match the HEAD commit.

You can use the following commands:

• To save your uncommitted changes

  git stash

• To list your saved stashes

  git stash list

• To apply/get back the uncommited changes where x is 0,1,2...

  git stash apply stash@{x}

Note:

• To apply a stash and remove it from the stash list

  git stash pop stash@{x}

• To apply a stash and keep it in the stash list

  git stash apply stash@{x}