HI. There are lots of different yoga mats out there; you can google yoga mats and see.....jade, hugger mugger, and ECO are a few.
As with many other things, it's good if you can check out a few types of mat before you buy. If you take classes at a few studios where you can rent a mat for a dollar or two, you may be able to 'test drive' a couple of mats to see what you like most in a mat.
The purpose of using a mat is to get some stability in your poses. So you don't slip. Some mats are very sticky, some less so but more cushioned. Different strokes for different folks, as they say.
There is also a BIG difference in price, too. And the most expensive mat may not be the mat that's best for you. If you don't have the opportunity to try out mats at some studio, I'd suggest going for the less expensive mat and checking that out. You may find that you like it a lot, and that would be great. Otherwise, I'd check out mats from Jade or ECO if you're going to be spending more money, because these companies specialize in yoga mats.
Good luck, and enjoy your yoga practice