For what is used?

#pragma comment

Answer 1, Authority 100%

Perhaps you should give examples:

// automatically puts libname.lib
#Pragma Comment (libname.lib ")
// automatically puts emapi.lib
#Pragma Comment (Lib, "Emapi")
// When calling the linker, an additional parameter / include: __ MySymbol will be used
#Pragma Comment (Linker, "/ Include: __ mysymbol")
// Row "Compiled on Data Compilation AT Time-Compilation" will be recorded in the EX file
// it will not affect anything, but will be visible in the Eggs in the form of text.
#Pragma Comment (User, "Compiled ON" __Date__ "AT" __time__)
// Same
#Pragma Comment (User, "Your Row, just will hang out in the exe file")
// The name and version of the compiler will be written to the Eshchnik. Not affect anything
// But it will be possible to see later.
#Pragma Comment (Compiler)

MSDN also says that

#pragma (exestr, "your comment")

Outdated and in future versions of the compiler will not be supported.

Instead, you can use:

# pragma (user, "your row comment")

Answer 2, Authority 12%

for Visual Studio places:

• version of the compiler (compiler),
• string (exestr),
• search library (lib),
• option for collector (LINKER),
• Arbitrary Comment (User)

to object file.

Answer 3

It should be noted that

# pragma comment

“Chip” exclusively Microsoft compiler. GCC does not know how. For what he and thanks.