[1] This allows one server to share its resources, such as memory and processor cycles, without requiring all services provided to use the same host name.
The term virtual hosting is usually used in reference to web servers but the principles do carry over to other Internet services.
This saves IP addresses and the associated administrative overhead but the protocol being served must supply the host name at an appropriate point.
A technical prerequisite needed for name-based virtual hosts is a web browser with HTTP/1.1 support (commonplace today) to include the target hostname in the request.
There is an extension to TLS called Server Name Indication, that presents the name at the start of the handshake to circumvent that issue, except for some older clients (in particular Internet Explorer on Windows XP or older Android versions) which do not implement SNI.
Furthermore, if the Domain Name System (DNS) is not properly functioning, it is difficult to access a virtually-hosted website even if the IP address is known.
Users should be careful when doing this, however, as any changes to the true mapping between host name and IP address will be overridden by the local setting.
The client is not involved in this process and therefore (unlike with name-based virtual hosting) there are no compatibility issues.
Many business companies utilize virtual servers for internal purposes, where there is a technological or administrative reason to operate several separate websites, such as a customer extranet website, employee extranet, internal intranet, and intranets for different departments.