Identifer versus keyword

Question

I read in the book for OCJP for Java6 the part with assertions. I reached the part where it gives me an overview of how the compiler reacts if the word \'assert\' is used as key

Answer 1

The terms "keyword" and "identifier" are not Java specific.

A keyword is a reserved word from the Java keyword list provide the compiler with instructions. As keywords are reserved, they cannot be used by the programmer for variable or method names.

Examples:

final
class
this
synchronized

Identifiers are the names of variables, methods, classes, packages and interfaces. They must be composed of letters, numbers, the underscore _ and the dollar sign $. Identifiers may only begin with a letter, the underscore or a dollar sign.

Examples:

int index;
String name;

index and name are valid identifiers here. int is a keyword.

A keyword cannot be used as an identifier.