What do you call performances that take place before the official opening night of a play?

The term for performances that occur before the official opening night of a play is "preview." Previews are special performances that allow the cast and crew to refine the production while also giving audiences a first look at the show. These performances often take place over several days or weeks leading up to the official opening, allowing the creative team to make adjustments based on audience feedback and the overall flow of the production. Previews are valuable for both the performers and the audience, as they create an atmosphere of excitement and anticipation for the official debut of the play.

While "viewings" and "rehearsals" might be related to the process of putting on a play, they don't refer specifically to performances intended for an audience before the official opening. "Previews," while similar in wording, is redundant in the context of this question as "preview" already encapsulates the concept of an initial performance prior to the official start, thus affirming that the correct term is indeed "preview."