A Web site builder, as the name suggests, is a software application or a bundle of applications that lets the user create a Web site without knowledge of the underlying markup and scripting languages like HTML, JavaScript, PHP, ASP and so on. Therefore it must be distinguished from an HTML editor. Often it will offer the user a collection of templates, pre-fabricated web pages that can be modified by the user. Some will also offer additional features like shopping carts or surveys.

Web site builders can be divided into online and off-line Web site builders. With an off-line application users will edit the site on their local computer and then publish it to the Web server. With online applications users edit their site using a Web browser.

Most web site builders are proprietary tools provided by web hosting companies which provide to people who wish to build their own websites without learning the technical aspects of web page creation. 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.