What is an episiotomy? Is it really necessary?

Perineal massage is known to help to avoid episiotomy cut during labour. I bought Weleda perineum massage oil to perform the massage. I end up with an episiotomy because I was too pain to inform the gynae that I don't want the cut. So the lesson learnt is remember to inform gynae in 3rd trimester about your plan. I have a closed friend who did the massage and manage to give birth without an episiotomy. However, it also depends on individual situation e.g pelvic size, size of the baby and etc. to decide whether episiotomy can be avoided. http://www.weleda.co.uk/baby+pregnancy-range/perineum-massage-oil/invt/606161