Domain names serve to identify Internet resources, such as computers, networks, and services, with a text-based label that is easier to memorize than the numerical addresses used in the Internet protocols. A domain name may represent entire collections of such resources or individual instances. Individual Internet host computers use domain names as host identifiers, also called host names. The term host name is also used for the leaf labels in the domain name system, usually without further subordinate domain name space. Host names appear as a component in Uniform Resource Locators (URLs) for Internet resources such as web sites (e.g., en.wikipedia.org).
A complex site calls for a more comprehensive package that provides database support and application development platforms (e.g. ASP.NET, ColdFusion, Java EE, Perl/Plack, PHP or Ruby on Rails). These facilities allow customers to write or install scripts for applications like forums and content management. Also, Secure Sockets Layer (SSL) is typically used for websites that wish to keep the data transmitted more secure.
Shared web hosting is the most affordable type of domain hosting available. Its affordability is due to the fact that you share a server with various companies who also want a low-cost web hosting plan. Each company that shares this server has its own specified amount of storage space that is defined by the hosting package Depending on the size of the server, you could possibly have thousands of websites hosted on the same platform, with each user receiving an allotment of the total available bandwidth, memory, and power.
Linux is the most commonly-used operating system for web hosting in the world, and Linux servers are a popular choice for many websites and applications. It is the industry-standard operating system, and in fact, one of the most popular groups of applications used to back websites is commonly referred to as LAMP, which stands for Linux, Apache (a web server), MySQL (a database), and PHP.
A fully qualified domain name (FQDN) is a domain name that is completely specified with all labels in the hierarchy of the DNS, having no parts omitted. Labels in the Domain Name System are case-insensitive, and may therefore be written in any desired capitalization method, but most commonly domain names are written in lowercase in technical contexts.
Next are third-level domains, which are written immediately to the left of a second-level domain. There can be fourth- and fifth-level domains, and so on, with virtually no limitation. An example of an operational domain name with four levels of domain labels is sos.state.oh.us. Each label is separated by a full stop (dot). 'sos' is said to be a sub-domain of 'state.oh.us', and 'state' a sub-domain of 'oh.us', etc. In general, subdomains are domains subordinate to their parent domain. An example of very deep levels of subdomain ordering are the IPv6 reverse resolution DNS zones, e.g., 22.214.171.124.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa, which is the reverse DNS resolution domain name for the IP address of a loopback interface, or the localhost name.