Lets say stock trading at 50.00 now and you want to buy if price drop to 49.80 or cheaper, you will put a "Limit order" buy order at 49.80.
But lets say you don't know which way market will go, and it's trading at 50.00, You want to buy at 50.20 or cheaper, if price touches 50.25 (then you put "LIT Order" for buy) or if price touches 49.80 and you want to short sell at 49.85 or higher (then you put "LIT Order" for sell or short depends on platform)