As far as I know "salary" refers to how much money you make monthly, especially if you are a teacher or a lawyer.

And "wages" refer to how much you make weekly or hourly especially if you work in a factory or in a shop.

If I have a friend who works, say, in a factory and I want to know how much money he makes monthly, can I ask him: What is your salary? or rather What are your wages?

In the US, we tend to think of "salary" as a yearly income, not monthly. A "salaried" worker is not paid by the hour, but on an annual basis, usually divided by 26 for a bi-weekly paycheck.

In the US, it's considered very rude to ask someone how much they earned. It's considered a very private matter and it simply not discussed.

If you were considering working for a company that you know a friend worked for, you could say something like "Does the pay tend to be good there? What type of salary might I expect?" (If you are going to be a salaried worker.)

If you are an hourly worker, you could say "What sort of pay might I expect?"

However, it utterly inappropriate to say "How much do you make?" or "What's your salary?" or "How much are you paid?"
In the UK, salary is also your annual amount, usually paid monthly. Wages usually refers to weekly pay or people who are not salaried (work varying hours for example) but paid monthly.

I can't think of a way to ask someone what their salary is either...really taboo here. About the nearest is a vaguer 'what's the pay like?' or 'Is it good pay' and they'll respond that it's pretty good, or ok, or terrible - but not with the amount!
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