Web part
Web Parts is a free add-on ASP.NET technology to Windows SharePoint Services. Web parts is an integrated set of controls for creating Web Sites that enable end users to modify the content, appearance, and behaviour of Web pages directly from a browser.
The modifications can be applied to all users on the site or to individual users. When users modify pages and controls, the settings can be saved to retain a user's personal preferences across future browser sessions, a feature called personalization. These Web Parts capabilities mean that developers can empower end users to personalize a Web application dynamically, without developer or administrator intervention.