The interpreters are stationed in a booth, use headphones to listen to the speakers, and translate what they say into the microphone with a 2 or 3-second delay. The audience (listeners) wear receivers on their ears to listen to the interpreters. Simultaneous interpreting requires an extraordinary amount of concentration because the interpreter must listen to what the speaker is saying at the same time as they are translating what has already been said.
Depending on the length and nature of the meeting, simultaneous interpreting teams usually consist of 2-4 interpreters working in a 15-20 minute rotation.
Simultaneous interpreting tends to be used mostly at major international conferences, large meetings and long meetings.

In consecutive interpretation, the speaker and the interpreter take turns talking. This format is probably what people most associate with the word "interpreting." In consecutive interpretation, the speaker talks until a logical break point is reached, and then the interpreter interprets what has been said to that point. This is repeated over and over. Only one person, either the speaker or the interpreter, is speaking at any time.

"Whispering" is a format for situations in which only a handful of people (1-3) in the audience require interpreting and there is no need to slow the meeting down just for them. The interpreter listens to the speaker directly without headphones, is stationed close to the listeners, and whispers the interpretation in their ears. (Simple microphones and receivers may be used in some situations.)