You have prepared your talk carefully. Then comes the part you cannot prepare: the questions. For many speakers, this is the most frightening moment.
It does not have to be. Questions mean people were listening. Here is how to handle them well.
Listen to the whole question. Do not start forming your answer halfway through. Let the person finish.
Repeat or rephrase it. This makes sure everyone heard it and gives you a few seconds to think.
Answer briefly. Long answers lose the room. Make your point, then stop.
Say "I don't know" when you don't. Then offer to find out, or ask if anyone in the audience knows. Honesty builds more trust than bluffing.
Treat hostile questions kindly. Stay calm, acknowledge the concern, answer the substance, and move on. The audience is usually on the side of the calm person.

