Lotteries are any form of assigning an award where there is an element of randomness or chance.
One example is a prize-linked savings account (PLSAs). One of the earliest of these was the Million a Month Account (MAMA) in South Africa, where First National Bank offered account-holders with qualifying deposits a chance to win up to one million rand each month (along with other smaller prizes given out at random).
Lotteries may be used with non-financial rewards as well, e.g. offering tickets to a sold-out play or sporting event for employees reaching certain performance benchmarks.