HIIT is any form of exercise that consists of a short burst of intense exercise that precedes a period of rest or low intensity exercise. The period of intense exercise can vary from less than 45 seconds to a few minutes. People then rest or do gentle exercise for a similar time frame before repeating the sequence. An entire HIIT workout may be as short as 15–20 minutes, but it provides a wide range of benefits. Its short duration can make it a very practical and effective choice for people who find it difficult to commit to longer sessions. HIIT also requires no equipment so people can do it anywhere at a time that suits them.