Which tag is used to define a client-side image map?

The tag used to define a client-side image map is the <map> tag. This HTML element is essential for creating interactive areas within an image, allowing for specific regions of an image to be hyperlinked to different destinations on the web. When you use the <map> tag, it works in conjunction with the <img> tag, which displays the image that has the associated clickable areas described by the <area> elements within the <map> tag.

Each <area> element within the <map> defines the shape of the clickable area (like rectangles, circles, or polygons) and specifies the link associated with it. Therefore, the <map> tag serves as a container for these definitions, linking the image to interactive functionality.

Using the <image-map> and <img> tags may appear similar, but neither of these provides the necessary framework for defining the regions of interactivity as the <map> tag does. The <area> tag is integral to specifying the clickable parts but does not stand alone as the definition of the map itself. Thus, the correct choice is the <map> tag, as it properly encapsulates the entire image map functionality.