The Use of typedef C Under Windows in C programming language

Take a look at the following declarations:
COLORREF color ;
HANDLE h ;
WPARAM w ;
LPARAM l ;
BOOL b ;

Are COLORREF, HANDLE, etc. new datatypes that have been added in C under Windows compiler? Not at all. They are merely typedef’s of the normal integer datatype.
A typical C under Windows program would contain several such typedefs. There are two reasons why Windows-based C programs heavily make use of typedefs. These are:

(a) A typical Windows program is required to perform several complex tasks. For example a program may print documents, send mails, perform file I/O, manage multiple threads of execution, draw in a window, play sound files, perform operations over the network apart from normal data processing tasks. Naturally a program that carries out so many tasks would be very big in size. In such a program if we start using the normal integer data type to represent variables that hold different entities we would soon lose track of what that integer value actually represents. This can be overcome by suitably typedefining the integer as shown above.

(b) At several places in Windows programming we are required to gather and work with dissimilar but inter-related data. This can be done using a structure. But when we define any structure variable we are required to precede it with the keyword struct. This can be avoided by using typedef as shown below:
struct rect
{
int top ;
int left ;
int right ;
int bottom ;
} ;

typedef struct rect RECT ;
typedef struct rect* PRECT ;

RECT r ;
PRECT pr ;
What have we achieved out of this? It makes user-defined data types like structures look, act and behave similar to standard data types like integers, floats, etc. You would agree that the following declarations
RECT r ;
int i ;
are more logical than
struct RECT r ;
int i ;
Imagine a situation where each programmer typedefs the integer to represent a color in different ways. Some of these could be as follows:
typedef int COL ;
typedef int COLOR ;
typedef int COLOUR ;
typedef int COLORREF ;
To avoid this chaos Microsoft has done several typedefs for commonly required entities in Windows programming. All these have been stored in header files. These header files are provided as part of 32-bit compiler like Visual C++