A website needs a Web server to run on, which is called the host computer. Some companies purchase and configure their own Web servers in-house. Along with complete control to determine the kind of server, networking and firewall configuration, internal hosting also comes with the the responsibility to ensure the website always stays up, that response time during normal and peak periods is acceptable and that maintenance such as data backups are regularly performed. A company with internal hosting must to dedicate resources to monitor and maintain the network and servers associated with its websites.
Some companies choose to outsource their website hosting to a vendor that specializes in hosting websites. The company usually leases the Web servers it needs and pays fees based on Web server capability, storage used and traffic received. With external hosting, the vendor usually guarantees a certain level of server up-time and network connectivity, such as 99.9 percent, performs backups and maintenance tasks and can often automatically increase a server's capacity if an unexpected surge of visitors slows down the server. If there is a problem, however, the company must work with the vendor to get the problem resolved.