Betta Splendens are very hardy fish. If taken care of well they can survive and thrive for years. They are a very unique fish and do not need any kind of aeration. They can live in smaller then normal tank ( But that doesn't mean they like it).
There are various variations in bettas the more common are Halfmoon, Veiltail, Crowntails, and Plakats. Even though they are hardy you should always make sure you take good care of them.
Below are some very good ebooks about setting up and caring for your betta splendens. And i recomend readin atleast one before buying and setting up a tank for them.

See the sites for more information about the ebooks.

Betta Lover's Guide * Recommended!

Betta Fish Secrets

Halfmoon Betta Fish Guide

Betta Fish Care Exposed

Thankyou for looking at my blog and may your bettas be happy and helathy

Matt