What exactly is Current working directory?

Question

My book states:

Every program that runs on your computer has a current working directory, or cwd. Any filenames or paths that do not begin with the r

Answer 1

os.getcwd() has nothing to do with OSX in particular. It simply returns the directory/location of the source-file. If my source-file is on my desktop it would return C:\Users\Dave\Desktop\ or let say the source-file is saved on an external storage device it could return something like G:\Programs\. It is the same for both unix-based and Windows systems.