Permission questions

[mss]

Hi,
Can someone explain this whole file/directory permission to me.

what is the diff between X and x . what is T and t used for?

why is it that when you create a file and type ls -l you see your username as the owner and the group by the same name? Does every user has its own group?

e.g.

-rwxrwxrwx #links username username size date filename

I want to know what the second username is for and what does it say about the file.

what is SUID, GUID and Sticky

and finally why is it that if you don't and x permission on a directory you can't see the content of the directory eventhough you have r permission?

Thanks in advance

[genesus]

That's big questions, take a look at this tutorial. There are much better one's out there; however, this is only one page long and has a pretty good diagram which explains what all of those x's r's and -s are.

http://www.hostingmanual.net/other/permissions.shtml

There are many others, but this'll do