In the case of simultaneous interpreting, the interpreter in the booth provides a continuous translation for the audience. There is virtually no time shift between the source text and the target text. The interpreter has to translate what has been said very quickly, and yet the translation has to be accurate and easily comprehensible.
In the case of simultaneous interpretation, a booth is required (for each language) with a good view of both the speaker and the audience. A microphone and headsets for the audience are also necessary.