What is the difference between ivf and icsi?

Definition: IVF is "in vitro fertilization" which could include ICSI - "intracytoplasmic sperm injection". IVF involves fertilizing an egg in a petri dish usually by putting a quantity, usually many millions, of viable sperm in the dish with an egg. IVF by ICSI involves using a single sperm that is injected into the egg to accomplish the fertilization. ICSI is used when there are very few sperm available.