A common question we've received is about when to use "lay/lie/laid/laying". In this post we cover the differences. Hope it helps to answer your questions.
Lay (principal parts: lay, laid, laid, laying) means "to put" or "to place." This verb requires an object to complete its meaning.
- In phase one, we will lay down the rules for the contest.
- I laid the message right on your desk.
- I had laid two other notes there yesterday.
- I've never been one for laying the blame on my subordinates. (Putting the blame.)
- The material was laid in the box. (A passive construction implying that someone laid the material in the box.)
Lie (principal parts: lie, lay, lain, lying) means "to recline, rest, or stay" or "to take a position of rest." It refers to a person or thing as either assuming or being in a reclining position. This verb cannot take an object.
- Now he lies in bed most of the day.
- The job lay before us as we negotiated terms.
- Our proposal has lain unanswered for two weeks.
- Your customer records are lying on the salesman's desk.
- I will (lie or lay?) down now. (You could not say, "I will place down now." Therefore, write "I will lie down now.")
- I (laid or lay?) the pad on his desk. ("I placed the pad on his desk" works. Therefore, write "I laid the pad.")
- I (laid or lay?) awake many nights. ("I placed awake" doesn't work. Write "I lay awake.")
- These files have (laid or lain?) untouched for some time. ("These files have placed untouched" doesn't work. Write "These files have lain untouched.")
- He has been (laying or lying?) down on the job. ("He has been placing down on the job" doesn't work. Write "He has been lying down.")
Source: The Gregg Reference Manual