If you're interested in waterproof camping tents due to the fact that you are going to be hiking and camping in possibly rainy areas, there are a lot of products you can buy; however, just because a tent manufacturer says its product is waterproof, this does not necessarily mean it is.
Yes, there was a waterproofing seal applied to probably the inside of the tent floor as well as possibly the rain fly and even maybe a foot up each side of the wall. But that's it, and this sealant is not going to last long if you don't apply some more product yourself.
Make sure the tent is completely dry and clean (preferably before you ever go camping in it). Apply the waterproof sealant to the bottom of the tent floor, at least 2 feet up all the tent walls, and along all seams (anywhere rain might be able to sneak in) according to the product's instructions.
If you take the time to do this prior to going camping, your odds of staying warm and dry will improve dramatically!
A couple other things you can do help keep your tent dry is to put a ground cloth or tarp underneath it or cover it with a rain tarp.
Shop for waterproof tents, tarps, water-repellent spray, and all sorts of other camping gear at Amazon.