Microsoft:

"Microsoft Office Web Components are a collection of Component Object Model (COM) controls for publishing spreadsheets, charts, and databases to the Web. They are also used to view these items when published and to view data access pages.

If you have Microsoft Office FrontPage 2003, Microsoft Office Access 2003, and Microsoft Office Excel 2003 installed, Office Web Components allow you to publish interactive data as part of a Web page. Used with Microsoft Internet Explorer version 5.01 or later, Office Web Components allow you to view a published control (spreadsheet, chart, or database) on a Web page and to view data access pages."