any = ‘it doesn’t matter who/which/what’

Any can be used to emphasise the idea of free choice, with the meaning of ‘it doesn’t matter who/which/what’. With this meaning, any is common in affirmative clauses as well as questions and negatives, and is often used with singular countable nouns as well as uncountables and plurals. In speech, it is stressed.

• Ask any doctor – they’ll all tell you that alcohol is a poison.
• My brother’s looking for work. He’ll take any job he can get.
• ‘When should I come?’ ‘Any time.’

We can use just any if necessary to make the meaning clear.

• I don’t do just any work – I choose jobs that interest me. (I don’t do any work … could be misunderstood.)

Note that we use either (see here), not any, to talk about a choice between two alternatives.

• I can write with either hand. (not … any hand.)

At all (see here) is often used to emphasise the meaning of (not) any.

• I’ll do any job at all – even road-sweeping.
• She doesn’t speak any English at all.