HostGator is a company I used for many years with an old firm, and I've found them to be fairly reliable as a rock-solid grounding for a bandwidth-heavy site. Their control panel is also fairly powerful, allowing you to automatically control your fleet of names, as well as locking them down so that nobody can snipe them if you accidentally let a renewal lapse. Their prices are competitive but not the best, but I've found them to be immensely reliable in the past.  Read our HostGator Review.
A domain name consists of one or more labels, each of which is formed from the set of ASCII letters, digits, and hyphens (a-z, A-Z, 0-9, -), but not starting or ending with a hyphen. The labels are case-insensitive; for example, 'label' is equivalent to 'Label' or 'LABEL'. In the textual representation of a domain name, the labels are separated by a full stop (period).

Name servers. Most registrars provide two or more name servers as part of the registration service. However, a registrant may specify its own authoritative name servers to host a domain's resource records. The registrar's policies govern the number of servers and the type of server information required. Some providers require a hostname and the corresponding IP address or just the hostname, which must be resolvable either in the new domain, or exist elsewhere. Based on traditional requirements (RFC 1034), typically a minimum of two servers is required.

Sedo is where I bought my domain - over Escrow - and is a global marketplace to buy, sell, and park domain names. They've over 18 million domain names for sale, but the big part is that they're a huge, well-respected company. This may not be important if you're spending $150 on a domain, but in a $15,000+ purchase - which happens in many cases - you will be potentially buying from a foreign entity, that you don't know, and many of them will suggest an escrow payment. This means you put the money in an account owned by a third party that will hold it and only pass it on once the domain has been transferred over into their name (which in this case is what Sedo does). This can be quite disconcerting - but Sedo is well-known and has done many, many deals - and the process is about as full of hand-holding as handing tens or hundreds of thousands of dollars for a domain name can be.
Domain names can be used in a number of ways. Direct visitors to your website’s home page or use complementary domains to send them to specific areas of your website ( e.g. for a careers page). Or, forward a custom domain to an existing social media account, like your Twitter profile or Periscope channel. With a domain name you can even set up custom email addresses like, which can be used to conduct business or communicate with your followers. More.