These two culprits are common causes for writers’ confusion. No wonder, they are so similar in form and meaning. To complicate matters even more, lie can show up as a verb and a noun. And lay as a verb, noun, and even an adjective. Let’s make it clear once and for all.
Lie
As a verb:
to be or to stay at rest in a horizontal position
to assume a horizontal position (lie down)
to make an untrue statement with intent to deceive or to create a false or misleading impression
a statement the speaker or writer knows to be untrue with intent to deceive or an untrue or inaccurate statement that may or may not be believed true by the speaker or writer
to have sexual intercourse (lie with)
to be in a helpless or defenseless state (lie at mercy of…)
to have direction or to occupy a certain relative place or position (lie to the east, lie behind him…)
to have an effect through presence, weight, or relative position (worry lies on his shoulders)
Lie
Present tense
lie
Past tense
lay
Past participle
lain
Present participle
lying
As a noun:
the position or situation in which something lies (the lie of the beast)
something stated that misleads or deceives
Singular
Plural
lie
lies
Lay
As a verb:
to put or set down
to place for rest or sleep
to beat or strike down with force
to bring forth and deposit (hens lay eggs)
to impose as a duty, burden, or punishment (lay a tax)
to place (something not material) on something (lay stress on behavior)
to bring to a specified condition (lay waste)
to submit for examination and judgment
a partner for or act of sex
Lay
Present tense
lay
Past tense
laid
Past participle
laid
Present participle
laying
As a noun:
the way in which a thing lies or is laid in relation to something else (the lay of the country)
the state of one that lays eggs (fish coming into lay)
Singular
Plural
lay
lays
As an adjective:
of or relating to members of a religious house occupied with domestic or manual work (lay monk)
not of a particular profession, lacking extensive knowledge of a particular subject (the lay public)
And what is the problem?
As said and shown, these two words have similar forms and meanings. A slip of a finger can easily end up in an incorrect sentence. Or it is simply hard to remember the small differences and use lie and lay correctly.