Many web hosting companies offer "unlimited" as a plan feature. It is impossible for any provider to actually provide an unlimited amount of bandwidth or disk space. It's just not possible.

Web Hosting is a commodity. The main elements of any web hosting plan are disk space and bandwidth. Disk space is the space you have allotted on the web server to store your website. Bandwidth is an amount you have available to transfer web pages from the web server to the browsers of visitors to your site. Web pages and graphics consume bandwidth or capacity on the web. Bandwidth and disk space cost money.

The network lines that carry data around the web (optic fiber, cable, copper wire etc) have a finite capacity. There is a limit to the amount of data that can be transferred at any point in time. Likewise, the hard drive of a web server has a limited amount of space determined by the physical size of the hard drive.


Why Do Unlimited Plans Exist?
Most websites only consume a very small amount of bandwidth and disk space. Web hosting companies that provide unlimited anything as a plan feature on the fact that you won't use very much. Unlimited is a marketing trick to get your business. The web hosting market is very competitive. Although selling plans that pretend to be unlimited can seem dishonest, it does not mean that the hosting company will not provide good service. Check in the hosting company's Terms of Service: there will probably be a note about what "unlimited" really means.