To Clap or not to clap
For today's audience, behavior is a mixture of enthusiasm and respect. Concentration and silence in the theater are essential, out of respect for the stage performers, orchestra and fellow audience members. It's best to avoid things like wrapping paper, reading the program notes aloud, humming along, rummaging through purses, or anything that could disturb those around you.

However, opera aficionados are a boisterous lot, and their exuberance will show itself at appropriate moments. In comic opera, laughter is a primary goal, and you should never feel shy about laughing. In both comic and serious work, applause is generally shared after overtures, arias, ensembles, and acts. Don't worry too much about it, the rest of the audience will let you know when the moment is right.