IMDB

Internet Movie DataBase
Every actor wants credit on IMDb.  It's a history of where you've
been professionally in film, it is sometimes seen by casting directors,
and hey, it's really cool to show your friends.

But be careful.  Casting directors hate seeing "Uncredited" on your
IMDB page.  It means nothing to them but that you've been on set as
an extra, and that they have to take their precious time sorting through those
to see what you've really done in an on screen speaking role.
With a lot of uncredited films on your page, they might not even bother
looking to see if there's anything of substance, and then you've got
no chance of them having contact your agent to call you in for an audition.
I made the mistake years ago of putting some on my IMDB page a week
before my agent told me and all his other actors not to do that.
Now IMDB doesn't want to take the time, and they've refused to
take them all off.  I've tried numerous times, and some got removed in
the beginning, but a few are still there.

So don't expect you can put some there to fill the space
until you get credited speaking roles and then have them removed.
They could do you more harm than good.

And do NOT submit for a film credit when you were an extra, and
conveniently leave out the "Uncredited", to make it look like you
had a speaking role.  It's not good to try and fool a casting agent.
They know.  They know.  They will spot it immediately, and there's
a good chance they'll permanently delete you from their list.