Answer 1

RAII stands for "Resource Acquisition Is Initialization", and is more a coding idiom regarding the acquisition and release of resources by a C++ program. It is not some class or function implemented in Std or Boost lib.

The main idea is this: you acquire the resource in the ctor of a class and you release the resource in the dtor. So you are basically using a class (or struct) to wrap the resource. Now you can use the lifetime of an object of the class to implicitly manage the lifetime of the resource.

Something like:
class DeviceContext {
DeviceContext() {
hDC = CreateDC(..) ;
}
~DeviceContext() {
ReleaseDC(hDC) ;
}
HDC hDC;
};

It should be clear that the lifetime of hDC is tied to the lifetime of a DeviceContext instance and that the class is just a thin wrapper around the resource.

This can be quite useful, especially if your resource is complicated to create and/or destroy.