See what's in a stash without applying it

How do I see what is inside a stash without actually applying it?

From man git-stash (which can also be obtained via git help stash):

The modifications stashed away by this command can be listed with git stash list, inspected with git stash show, and ...

show [<stash>]
    Show the changes recorded in the stash as a diff between the stashed
    state and its original parent. When no <stash> is given, shows the
    latest one. By default, the command shows the diffstat, but it will
    accept any format known to git diff (e.g., git stash show -p stash@{1}
    to view the second most recent stash in patch form).

Note: the -p option generates a patch, as per git-diff documentation.

List the stashes:

git stash list

Show the files in the most recent stash:

git stash show

Show the changes of the most recent stash:

git stash show -p

Show the changes of the named stash:

git stash show -p stash@{1}

Or in short:

git stash show -p 1 

If you want to view changes of only the last stash:

git stash show -p 0