I was given permission to use this from another website, posted by a gent that goes by the handle, "Jack." It's a great piece on theater ettiquite--in this day and age, where so many people seem to have slipped backwards in evolutionary terms, and forgotten basic manners, and also, in a time--with home entertainment a major industry--many people have never been to the theater, and are a bit intimidated by the thought. This is a really great guide, I think, for everyone:
Arriving At The Theatre
It is probably best to arrive at the theatre at least half an hour before the performance starts. This will give you some extra time to collect your booked tickets, buy any pre-performance drinks and programmes that you may require and generally get comfortable before the curtain goes up.
The time on your ticket refers to the time when the performance begins, as opposed to when you should arrive at the theatre. It is always important to check the starting time on your ticket as they do vary from theatre to theatre and from performance to performance. Unlike a cinema, no adverts are shown before the show, so you must arrive on time! (See Theatre etiquette).
If you intend to drive to the theatre then it may be wise to give yourself extra time in order to find a parking space, as it can quite often be easier said than done - depending on the location of the theatre. Remember up to 1800 people could be arriving at the same time as you. Check with the box office which car parks they recommend and ask if there are any special deals with local car parks.
Alternatively, most theatres are near a bus route or you could park your car somewhere safe, away from the theatre, and take a taxi to the entrance. This will ensure that you aren't held up trying to park as the curtain rises!
Theatre Etiquette
One of the most unwelcome things in the theatre has to be the mobile phone. Mobile phones (along with anything else that bleeps, buzzes or makes any kind of electrical noise) should be switched off well in advance so as not to make your first visit to the theatre an unwelcome one!
Theatre regulation states that latecomers will not be admitted into the auditorium until a suitable break, or the interval so as not to distract the performers and the rest of the audience. If you are late, many theatres have a screen in the foyer / bar where you can watch the performance until there is a suitable opportunity for you to enter.
Cameras, video and tape recorders are strictly prohibited in the auditorium and smoking is not permitted except in designated smoking areas within the theatre. However, many theatres have now become entirely non-smoking.
Once you have taken your seats in the auditorium you are advised to remain in them until the interval as you will not be allowed back in until a suitable break in the performance - so make sure you are comfortable and have everything you need before the curtain rises.
Although the performance tends to be exciting and enjoyable, noise from the audience can be very distracting for the performers, so the audience will be expected to sit quietly in their seats during the performance.
What To Wear
There are still many people who believe that a trip to the theatre is out of the question because they have nothing smart enough to wear because their best evening outfit is still at the cleaners!
However, people no longer wear full evening dress, in fact, if you did, you would certainly stand out from the crowd! Instead, it is very much the case that anything goes; just make sure that you are comfortable. Some people do dress fairly smartly simply in order to make an evening out slightly more special but it really is no longer a requirement. Most clothing is acceptable.
This means that the theatre is far more accessible than it ever used to be, and so there really is nothing to stop you going along to see a production straight from home or work and experiencing some real magic of the theatre first hand.
Remember, you are there to be entertained. So enjoy!