Simultaneous interpreting requires lots of skill and experience and can be very tiring for an interpreter, which is why it is common for two interpreters to work in partnership.  They listen via a headset to the speaker and interpret what is being said into a microphone for the relevant audience members taking turns every 15/20 minutes. 

Simultaneous interpretation like this is commonly required at conferences involving several different languages and many participants.

Consecutive interpreting is probably the most common type of interpreting and is widely used. It is used for business discussions, negotiations, contract exchanges, commercial discussions, legal, technical or engineering discussions, medical or court hearings or on-site inspections. The interpreter listens to the speaker, often making notes, and later delivers the meaning in the target language. If a speech is delivered, the interpreter may wait until a pause or the end, delivering a translation relatively quickly. Consecutive interpreting may also be used at conferences for panel discussions, Q&A sessions or private discussions between parties - at a stall or elsewhere. 

Facilitating interpreting is used when a client has limited English / source language skills but requires technical or in-depth terminology to be clarified in their native tongue to avoid misunderstandings. The facilitating interpreter is there primarily to ensure communication is effective and relieve the client from the fatigue of speaking in a foreign language. 

Telephone interpreting allows parties of different nationalities who cannot meet in person to communicate via telephone or video conferencing. The interpreter bridges the gap.

Sometimes an interpreter is present in one of the two locations, and sometimes he/she is also located somewhere apart from both parties.