Time In Force

Microwaves have timers on them. If they didn't, you could forget about your popcorn, and come back an hour later to find an irradiated black husk.

Time-in-force orders play the same roles for stock traders. They represent stock orders tied to specific time instructions. They only remain in force for a particular length of time. That way, an active trader doesn't forget about a particular order they set, and end up with an irradiated black husk of a strategy.

You set an order to buy AAPL at $200 a share. It's trading at $205. It never really goes down. Three weeks later, it's trading at $225 and you've completely forgotten about the order. You move on to other things. Then news comes out that the United Apple Growers Association is suing the company over its trademark. Shares drop to $198. Your old, dusty buy order goes into play. It messes up your current strategy.

With a time in force order, this situation wouldn't come up. You'd put a time limit on the buy order, like an expiration. It prevents mistakes and guards against forgetfulness. Just like the microwave timer.