Hanger:  A frame for holding sheet film while processing in a tank.

Hard:  Describes a scene, negative, or print of high contrast.  Opposite:  soft or low contrast.

Heliography An early photographic process, invented by Niepce, employing a polished pewter plate coated with bitumen of Judea, a substance that hardens on exposure to light.

Highlight A very dense, dark area in a negative.

Hot shoe:  A bracket on the top of a camera that attaches a flash unit and provides an electrical connection to synchronize the camera shutter with the firing of a flash.

Hyperfocal distance:  The distance to the nearest plane of the depth of field (the nearest object in focus) when the lens is focused on infinity; also the distance to the plane of sharpest focus when infinity is at the farthest plane of the depth of field.  Focusing on the hyperfocal distance extends the depth of field from half the focal distance to infinity.  

Hypo A common name for any fixer; taken from the abbreviation for sodium hyposulfite, the previous name for sodium thiosulfate (the active ingredient in most fixers).

Hypo clearing agent or hypo neutralizing agent:  See Washing aid.