Most web site builers are proprietary tools provided by web hosting companies which cater to people who wish to build their own websites without learning the technical aspects of web page production. The person who wishes to use the website builder typically signs up with the company -- most offer free trial periods -- and chooses the design that best suits his or her purpose. Some companies' tools allow the user to see the source code, that is, the HTML behind the page he is building. Many do not, meaning that only certain designated areas on the page can be modified. Usually, these areas are: headers, text and some graphic elements.