What C++ idioms should C++ programmers use? [closed]

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What C++ idioms should C++ programmers know?

By C++ idioms, I mean design patterns or way of doing certain things that are only applicable for C++ or more applicable for C++ than most other languages.

Why one should use the idioms, and what do the idioms accomplish?

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By far the single most important "pattern" to learn and know that's (nearly) unique to C++ is RAII (Resource Acquisition Is Initialization).

Edit: (To answer extra question edited into the question). You use RAII primarily to (semi-)automate resource management. The most obvious use is freeing resources owned by objects when the owning objects go out of scope, such as freeing memory or closing files.

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Here is one list. If I had to pick a couple I might go with the Curiously Recurring Template Pattern or Virtual Contstructors.

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PIMPL, aka P ointer to IMPL ementation ?

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Template metaprogramming. It's great because it's basically compile-time duck typing, so you get most of the flexibility of duck typing with the speed of static typing.

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If you want to get the most out of the STL then iterators and functors/function objects are essential idioms. The use of iterators also implicitly relies on the 'half-open range' idiom too.

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Exploiting Strong Typing and const correctness is also extremely helpful.

I also prohibit default copy constructors and assignment operators. I actually go beyond that, but those are the most common. I think life would be easier if they were not implicit.

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RAII, COW, pimpl, law of demeter (not sure if can be classified as idiom), type traits and policies. (COW and law of demeter are not limited to C++ though)