It seems obvious that a domain name that is made up of exactly the kind of words that normal people would use to describe or find your web site on a search engine is the best type of domain name of all!  Famously many single word domain names are taken names like pizza.com for example. But even so there are many possible combinations of keywords that you can buy in a domain name that can help your web site. Here is a very funny video from you tube on this subject -kinda?!?