Well, it is free. You create an account with a password, decide your level of permissions and upload your photos. You can upload in bulk but be prepared for it to take a while if you have lots.
Then you can access your photobucket any time you are online, use the codes to post in a forum or a blog, copy to cd or dvd, send to your friends or family via email or just look at them.
It's a very handy backup if your pc goes kaput or if you want to see your photos when you using a different pc.
http://register.photobucket.com/
You can also store your videos.
I mainly use it as extra back up - sort of a free drive.