What does a typical modern theater show before movie trailers?

A typical modern theater presents commercial advertising shorts, then movie trailers, and after a feature film. Advertised start times are usually for the entire program or session, not the feature itself; thus people who want to avoid commercials and trailers would opt to enter later. This is easiest and causes the least inconvenience when it is not crowded or one is not very choosy about where one wants to sit.

Source: Wikipedia