'I need to lie down.' Choosing the right word: 'lie', 'lay' or a different 'lie'?

lie - lay - lie

How do you know which one to use? And if you do, how do you use them? Let's see...

These three little bad boys can cause lots of difficulties for English learners because they seem so similar. So, if you want to stop them from ruining your otherwise perfect life, you'll need to get to know these guys a bit better. Let's get down to business!

lie (1) - to say something that isn't true
Verb forms: lied (past simple), lied (past participle), lying (present participle)

e.g. Don't you lie to me!
I promised to tell you the truth, but I lied.
He's already lied to me, and I'm sure he'll do it again.
I have a strong feeling that you're lying to me.

Prepositions and idioms:
lie to somebody
lie about something
lie through your teeth (=say something that is completely untrue)

lie (2) - to be in a horizontal position
Verb forms: lay (past simple), lain (past participle), lying (present participle)

e.g. The doctor told me to lie down.
He just lay there, thinking about his life.
Sarah's been lying in the sun for about an hour.
Why are you still lying in bed?

Prepositions and idioms:
lie on
lie still
lie awake
lie down

lay - to put something down on a surface
Verb forms: irregular verb; laid (past simple), laid (past participle), laying (present participle)

e.g. You can lay this book on the table.

He laid his hand on my shoulder.

Rachel’s laying the table at the moment. (=She’s serving the table.)

Prepositions and idioms:
lay something on something
lay something somewhere
lay the groundwork (=provide the conditions for something to be successful)
lay down the rules (=say what the rules are)