If you get a domain name that describes your company's business or name, people can remember the name easily and can return to your site without having to consult their documents. My personal preference is to register the name myself, so that I can be sure that I am registered as the owner, the administrative and technical contacts. The various contacts are less vital, but still play important roles. For example, the administrative contact's approval is required before a domain name is transferred out of a web host. Domain names disappear extremely fast.
Many people claim that all the good domain names are gone.
I doubt that - but it is probably true that most good domain names that are descriptive of products and services have been taken. If you want a domain name for your site, I suggest you act now, or face the anguish of having lost that name later. Obtain from your web host the DNS IP address and names of their primary and secondary nameservers. Don't worry if you don't understand what these things mean. Just save the information somewhere.