You have a choice of many shells on Linux. For instance on the openSUSE v10.2 I'm on here, if I run the cmd
I get the following
those are all the shells available to me.
Try the same cmd on your system, you should get a similar list.
To see your default shell, ie the one the system assigns you at login, use
grep <yourusername> /etc/passwd
the last field is your shell.
Here is a really good Linux tutorial : http://rute.2038bug.com/index.html.gz