• Some is used in positive sentences. Any is used for negative sentences.

EXAMPLE: I have some peanuts for the monkeys.
EXAMPLE: I don't have any peanuts for the monkeys.

• We use some for questions with possible yes answers, and any for questions whose answers are uncertain.

EXAMPLE: Do you want some medicine for your cough?
EXAMPLE: Is there any medicine for my cough?

• Sometimes, we can use some and any instead of a/an when referring to quantity.

EXAMPLE: Is there a bird in that tree? Are there any birds in that tree?
EXAMPLE: There is an egg in the nest. There are some eggs in the nest.

• We can choose not to use some and any when referring to quantity.

EXAMPLE: There is some coffee for you. = There is coffee for you.
EXAMPLE: Are there any apples in the fridge? = Are there apples in the fridge?

• Some and any are used with countable nouns.

EXAMPLE: There are some letters for you.
EXAMPLE: Are there any letters in the mailbox?

• Some and any are used with uncountable nouns.

EXAMPLE: There is some tea in the pot.
EXAMPLE: Is there any tea in the pot?

• Some and any can be used without adding nouns if it is understood what is meant.

EXAMPLE: I can give you some. / Sorry, I don't have any to lend you.

• Some and any have other uses.

EXAMPLE: I have not seen a kangaroo for some years.
EXAMPLE: Any idea you have must not be ridiculous.

• Some is not normally used in descriptions.

EXAMPLE: He's got dark hair on his chest. (NOT: He's got some dark hair on his chest.)

• We do not use some to identify people or things.

EXAMPLE: Adam and Eve are family doctors. (NOT: Adam and Eve are some family doctors.)

• We can use some in questions.

EXAMPLE: Do you want some pineapple juice? (Uncountable noun)
EXAMPLE: Did you buy some scented flowers? (Countable noun)

• Some can be used on its own, somewhat like a pronoun.

EXAMPLE: Most in the audience were enjoying the performance, but some were sleeping.

• Any can be used in positive statements.

EXAMPLE: You can borrow any of my tools.

• We can use any in interrogative sentences.

EXAMPLE: Are there any problems with your work?

• Any can be used in a sentence with if.

EXAMPLE: If you had any brain, you wouldn't have done it.