The interpreter sits in a booth, in front of a microphone, listens through headphones to the incoming message in the source language and communicates it over the microphone to whoever is listening in the target language.
Simultaneous interpretation is advisable for meetings in which a number of languages are spoken and with a large number of participants. Interpreters always work in teams of 2 or 3.
The interpreter sits at the conference table with the delegates, listening to whoever is speaking in the source language and makes notes as the speech progresses.
When the speaker has finished, the interpreter consecutively reproduces the message in the target language as though s/he were making the original speech.