What is a Domain Name?
A domain name gets you the "www.mycommunity.com" name.
Is this important? Yes! Put some thought into what domain name you want. Most domain name providers will tell you which names are/aren't available.
Remember that in order to find your site, people will most likely begin typing something into a search engine (Google, Bing, etc.). If your domain name is cumbersome or difficult to remember, it will make it harder for people to find you.