http://qz.com/165238/the-biggest-land-rush-in-the-history-of-the-internet-begins-on-february-4/

Domain names, the basis of web addresses, are overseen by the Internet Corporation for Assigned Names and Numbers (ICANN). They follow a hierarchy, much like physical addresses. If the web were a country, then a generic top-level domain like .com might be the state or province, and a second-level domain, like google.com, would be a city. Neighborhoods within the city can be found in either a suffix (google.com/images) or a prefix (images.google.com).