Any is a determiner that suggests an indefinite amount or number. It is used when it is not important to say how much or many we were thinking about. Any is often used in questions and negatives. It is not very common in affirmative clauses.

Have you got any rice?
Did you have any trouble going through customs?
You never send me any gift.
Any is common after if in affirmative clauses.

If you need any help, just give me a call.

Any may also emphasize the idea: ‘it doesn’t matter who, what, which’.

Any and some
Like any, some is also a determiner expressing an indefinite amount or number. Some is more common in affirmative clauses.

Compare:

Do you have any money?
No, I haven’t got any money.
Yes, I have got some money.

Any, not any and no

Any alone does not express a negative meaning. To be negative any should be used with not.

She was unhappy because she didn’t get any gifts. (NOT She was unhappy because she got any gifts.)

No means the same as ‘not any’, but it is more emphatic.

She has got no money. (More emphatic than ‘She hasn’t got any money’)

Notes

You cannot begin a sentence with ‘not any‘. Instead, no is used.

Any and a/an
Any is often used with uncountable and plural nouns. It has more or less the same meaning as ‘a/an’ has with singular countable nouns.

She has a friend in that city.
She hasn’t got any friends in that city.