(2) In graphics software, a sizable and movable frame that identifies a selected portion of a bit-mapped image. The marquee frame can be rectangular in shape or, in some cases, irregular. A lasso tool, for example, enables you to select all contiguous portions of an image that share the same color.

The marquee frame is usually displayed with a flashing dashed line. In fact, that explains the origin of the name, since the dashed lines look a little like the flashing lights around a theater entrance, which is also called a marquee.

Explanation of HTML marquee tag
Description of how to use the marquee tag in Web pages. Lists related attributes along with examples, as well as information on which browser (and version) supports this element.