Weather you've just started looking into buying your own yoga mat or have been looking at them for a while, it can be so confusing deciding what type of mat to buy. Even after you've had your own mat, you may find that you don't like your mat as much as you thought you did. I think that what happens a lot of the time is that people will buy any yoga mat to start with, and then after practicing on it start to realize that not all yoga mats are created equal, and the one they purchases might not be the best one for them.
There are 2 main types of yoga mats- closed cell mats and open cell mats. Closed cell mats are the ones that have that pattern in the material that looks like rows of little tiny squares. Open cell mats lack this texture- they are more "raw" looking- you might even see little holes when you look closely.
One of the big benefits of having a closed cell mat is that they are usually cheaper and can be easier to keep clean. They aren't as absorbent and can usually be cleaned with a wider variety of cleaners. These mats are also available in a variety of thicknesses- which can be very nice if you'd like some extra cushion under the knees in a pose. The con to this type of mat is also that it is not absorbent. If you've ever taken a class where you've gotten very sweaty or just have sweaty palms during class, you know that sliding on the mat can be a real struggle with closed cell mats.
On the other hand, open cell mats are usually made of natural rubber and they are very absorbent. With these types of mats, sliding is usually not an issue at all, however you will be paying for the difference in grip on these mats. With open cell mats, you may have to be careful how you clean the mat as it will absorb anything used on it. The natural rubber can give off a smell at first, and can dry out over time.
Really, the type of yoga mat that you choose will depend on how you're practicing. If you tend to go to classes that require a lot of grip, maybe an open cell mat is better for you. If you need a thicker mat or want a mat that you can throw onto the grass to practice on without absorbing anything, a closed cell mat would probably be more beneficial. I'd recommend finding a studio space that allows you to rent or borrow a mat and see how you like the mats provided before deciding which one to purchase, as they can be kind of pricey.