A lot of the idioms you find in books that teach English are quite dated. Raining cats and dogs is almost never used, and go bananas is also quite dated and uncommon. Both idioms would be readily understood by almost anyone, however. There are countless idioms. The more you read and listen the more you will come across. You are better off learning idioms in context because some will generally only be used in quite specific situations. This list seems fine: https://www.ef.edu/english-resources/english-idioms/ From that list, I think these are NOT used often or I have NOT heard be used personally: Miss the boat On the ball > We generally use the idiom "to drop the ball" meaning to mess up or worse than you could Speak of the devil > common but almost always "speaking of the devil" Every cloud has a silver lining It's raining cats and dogs There's no such thing as a free lunch A lot of the proverbs on that list I haven't heard personally.

Idioms, sort of exist because people use them, making them idioms :) . Yep, we use them. Go nuts! Use them all the time.

Use them! Knock yourself out.

One thing to be aware of with idioms is that many of them vary a lot from country to country, age group to age group, and even within societal sub-groups. If you are going to use an idiom, it pays to know how universal it is, and if it isn't universal, which groups you can safely use it with. Cole's comment is an example of that. His age group don't tend to use the phrases that he called dated. My age group probably still use them - to some degree.

I think idioms are used in every language.