A website domain, sometimes just called a domain, has different related meanings. Most commonly, a website domain is the name of the website or URL, and is sometimes called the host name. The host name is a more memorable name to stand in for the numeric, and hard to remember, IP address of a website. This allows the website visitors to find and return to a web page more easily. It also allows advertisers the ability to give a website a memorable name that visitors will remember and come to, hopefully leading to conversions for the web page. The flexibility of website domains allows several IP addresses to be linked to the same website domain, thus giving a website several different pages while remaining at the easily remembered address.
Website domains are generally restricted to certain letters and numbers of the general ASCII standards. This is the letters a through z, and the numbers 0 through 9 in different combinations. In some cases they are also allowed to use a hyphen. All website domains are restricted to valid host names so that the website domains that are chosen are not useless to the people who pay for them. Every website domain also ends in what is called a top-level domain, which is a two or three letter reference that has something to do either with the country of origin, such as .us for the United States, or with the type of web page it is, such as the very popular .com for commercial web pages.