git add * (asterisk) vs git add . (period)
add * means add all files in the current directory, except for files whose name begin with a dot. This is your shell functionality and Git only ever receives a list of files.
add . has no special meaning in your shell, and thus Git adds the entire directory recursively, which is almost the same, but including files whose names begin with a dot.
* is not part of git - it's a wildcard interpreted by the shell. * expands to all the files in the current directory, and is only then passed to git, which adds them all.. is the current directory itself, and git adding it will add it and the all the files under it.
Using the dot . in the shell usually means "the current directory".
When you use the asterisk * on a shell a feature called file-globbing is utilized. E.g. on bash the function glob() is doing just that. The manpage for glob (man 7 glob) states:
DESCRIPTION
Long ago, in UNIX V6, there was a program /etc/glob that would expand wildcard patterns. Soon afterward this became a shell built-in.These days there is also a library routine glob(3) that will perform this function for a user program.Wildcard matching
A string is a wildcard pattern if it contains one of the characters '?', '*' or '['.Globbing
Globbing is the operation that expands a wildcard pattern into the list of pathnames matching the pattern.
That means when you pass arguments to any program on the commandline that contain '?', '*'or '[', first globbing expands the wildcard pattern into a list of files and then gives these files as an argument to the program itself.
The difference in meaning between 'git add .' and 'git add *'is clearly described by Denis:
git add expects a list of files to be added. In the above example the shell expands * or . respectively and gives the result as a parameter to git add. Now the difference is that with git add . git will expand to the current directory whereas git add * triggers file globbing and such expands to all files and directories that do not start with a dot.