Definitions for DNS Server Settings?

I am looking at master DNS settings on my Enom domain. I'm wondering what the difference is between the following....

www
@
*

www is a bit obvious, but what about the others? What is @ if it doesn't apply to email? At least, the MX records relate to all of the email, right?

From serverfault Webnet

• The * character is used to denote a wildcard record. A wildcard is basically used to provide an answer for to questions related to records that don't exist in your zone.

  The www is just a typical name.

  The @ character is a special character that usually as shorthand for the current domain. So for the zone example.org the @ characters is shorthand for example.org.

  Also see:

  • http://en.wikipedia.org/wiki/Zone_file
  • http://tools.ietf.org/html/rfc1035
  From Zoredache

• Let's say your domain record for nowhere.net has these two entries:

  @ IN A  78.90.12.34
  * IN CNAME nowhere.net.
  

  The @ sign in a record means the domain itself with no host, i.e. nowhere.net. This would allow someone to put http://nowhere.net in their browser and resolve to 78.90.12.34.

  The * sign in a record is a wildcard for any hostname. You could enter www.nowhere.net, ftp.nowhere.net, mail.nowhere.net, yo-mama.nowhere.net, etc. and they would all resolve to the IP specified for the domain. You wouldn't have to set each one up with a separate record.

  From Roman