hand lens

A magnifying glass is a convex lens that is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle. A magnifying glass can be used to focus light, such as to concentrate the sun's radiation to create a hot spot at the focus for fire starting.

Text seen through a magnifying glass

Jim Hutton as detective Ellery Queen, posing with a magnifying glass

A plastic Fresnel lens sold as a TV-screen magnifier

A sheet magnifier consists of many very narrow concentric ring-shaped lenses, such that the combination acts as a single lens but is much thinner. This arrangement is known as a Fresnel lens.

The magnifying glass is an icon of detective fiction, particularly that of Sherlock Holmes.