Web hosting refers to the provision of serviced web space for clients. The web hosting company has an advanced connection to the major connections that make up the internet. This connection is linked to computers/severs under the control of the web host. Clients then rent space on the hard drives of the web-hosts servers.
There are many benefits to using a web host rather than hosting a website on your own computer. Such as 24hrs, 7 days a week, 365 days a year uptime, technical support.