Accelerators were a form of selection-based search which allowed a user to invoke an online service from any other page using only the mouse; they were introduced by Microsoft in Internet Explorer 8. Actions such as selecting the text or other objects gave users access to the Accelerator services (such as blogging with the selected text, or viewing a map of a selected geographical location), which could then be invoked with the selected object.

According to Microsoft, Accelerators eliminated the need to copy and paste content between web pages. IE 8 specified an XML-based encoding which allowed a web application or web service to be invoked as an Accelerator service. How the service would be invoked and for what categories of content it would show up were specified in the XML file. Similarities have been drawn between Accelerators and the controversial smart tags, a feature experimented with in the IE 6 Beta but withdrawn after criticism (though later included in MS Office).

Support for Accelerators was removed in Microsoft Edge, the successor to Internet Explorer.

Microsoft introduced accelerators in Internet Explorer 8 Beta 1 as "activities." It was later renamed to "accelerators." in IE 8 Beta 2.

Accelerators were included in IE8 by default as a type of add-on.

This is an example of how to describe a map Accelerator using the OpenService Format: