Here are some shells:

• Bourne (sh): this is the original Unix shell, available in nearly every flavor of Unix.
• Korn (ksh): a backwards-compatible upgrade to the Bourne shell, developed by David G. Korn at AT&T Bell Laboratories.
• Bash (bash): Bourne-again shell, a public domain shell containing features of the Bourne, Korn and c-shell.
• C-Shell (csh) and T-C-Shell (tcsh): The c-shell is similar to C programming language; t-c-shell extends csh.
• Z-Shell (zsh): an open-source Unix shell.

You can see what shells are available on your system like this:

$ cat /etc/shells

You can see what shell you are currently using like this:

$ echo $SHELL