A photomask is an opaque plate with transparent areas that allow light to shine through in a defined pattern. Photomasks are commonly used in photolithography for the production of integrated circuits to produce a pattern on a thin wafer of material. In semiconductor manufacturing, a mask is sometimes called a reticle.

Photolithography is a process used in the manufacturing of integrated circuits. It involves using light to transfer a pattern onto a substrate, typically a silicon wafer.