Theatre criticism is a genre of art criticism, and the act of writing or speaking about the performing arts such as a play or opera.
Most major national newspapers of first world countries cover the arts in some form and theatre criticism may be included as a part of this arts coverage.
Specialist media exists to cover most artistic disciplines, in this field one such publication is The Stage (see our theatre magazines category for more).
As with other forms of criticism it may use its own technical language to convey what the reviewer has seen.
A notable theatre critic is Kenneth Tynan.