Sometimes abbreviated as vhost, this is a provider of web-services that include server functions and internet connection serves.
Companies and individuals who do not wish to purchase and maintain their own web-servers and internet connections may use a virtual host.
Virtual hosts provide its consumers with domain name registration, directory serves, e-mail, file storage, and even website design.
The downfall to using a virtual host is the consumer shares the web-services with other consumers of the virtual host. If there are multiple sites running off the same server those sites begin competing for web resources.
Consumers do have the option of some virtual hosting that provides co-location serves and/or allows a customer to rent dedicated servers that server only that consumer.