A system called DNS (Domain Name System) is used to resolve friendly domain names to less friendly IP numbers that are used to actually address and route traffic across the internet. The registration of domain names is controlled by a set of domain registrars that are assigned different top-level domains (TLDs). The TLD is the highest level of hierarchy and is the portion of the domain name that appears furthest to the right, Some common TLDs are .COM, .NET, and .ORG. The next part of the domain name is referred to as a second-level domain names (SLD). It is the part that appears just to the left of the TLD.