Simultaneous is an adjective that means occurring at the same time. Simultaneous interpreting is interpreting (verbally translating) a speaker as he/she speaks. This concurrent form of interpreting requires the combination of many skills of conference interpreters with specialised conference equipment.
There are ISO standards for simultaneous interpreting, which relate to both the technical equipment (such as the booths or audio & visual componenets) and the service aspects, i.e. availability of a technician,
Simultaneous interpreting was first performed during the Nürnberg trials following thr World War II.