C++: What is the difference between identifier, keyword, name and entity?

In the following, is "identifier" a name of a variable i? Is int a "keyword"?

int main()
{
     int i;
}

I'm not being able to understand the difference between a keyword, identifier, name, entit开发者_StackOverflow中文版y.

For the variable int i, int is the type and i the name. For the variable itself, i would be the identifier; however, int is the identifier for the type.

Types may be, but are not always, keywords. Identifiers refer to a certain object, type, etc. Names refer to an instance of an object. Entities refer to any sort of object, including basic types (int, char, etc).

i is an identifier here. int is a type, actually a data type.

Identifiers:
Definition from MSDN:

An identifier is a sequence of characters used to denote one of the following:

• Object or variable name
• Class, structure, or union name
• Enumerated type name
• Member of a class, structure, union, or enumeration
• Function or class-member function
• typedef name
• Label name
• Macro name
• Macro parameter

Keywords:

C++ reserves a set of 63 words for it’s own use. These words are called keywords, and each of these keywords has a special meaning with in the C++ language.

Check out the list of keywords here.

Good Read:
What are identifiers?
What are keywords?