Linking is the step where the separate compilation units are joined together, in the case of using external libraries, this is also where the library code is linked into your application code.
You can get a variety of linker errors, the most common ones I would expect you to see would be an 'unresolved external symbol' where you have declared something but not defined it, or a 'multiply defined symbol' error where you have managed to put something in a header file such that it is duplicated into multiple compilation units instead of being referenced by multiple compilation units.
tl;dr Learn what the C++ compiling process involves (pre-processing, compilation, linking)
Also, this should really be in the C++ programming forum. Can a mod move it?
You can get a variety of linker errors, the most common ones I would expect you to see would be an 'unresolved external symbol' where you have declared something but not defined it, or a 'multiply defined symbol' error where you have managed to put something in a header file such that it is duplicated into multiple compilation units instead of being referenced by multiple compilation units.
tl;dr Learn what the C++ compiling process involves (pre-processing, compilation, linking)
Also, this should really be in the C++ programming forum. Can a mod move it?
The little boat gently drifted across the pond exactly the way a bowling ball wouldn't.