# Windows Paths | | | | --- | --- | | **Path** | **Description** | | C:\\Documents\\Newsletters\\Summer2018.pdf | An absolute file path from the root of drive C: | | 2018\\January.xlsx | A relative path to a file in a subdirectory of the current directory. | | ..\\Publications\\TravelBrochure.pdf | A relative path to file in a directory that is a peer of the current directory. | | F:\\Projects\\apilibrary\\apilibrary.sln | An absolute path to a file from the root of drive F: | A file extension is three or four characters at the end of a filename, such as .DOCX, .PDF or .TXT. File extensions tell you the file type, and which programs can open it. File extensions aren't necessary in MacOS or Linux. # MacOS and Linux No drive letters. Everything is treated as a file * Forward slash, not back slash e.g. /usr/bin/python3 or /etc/os-release * . Current directory * .. Parent directory * ~ Home directory .filename hidden files have a . at the front # Windows Shell Commands cd change directory * dir display directory contents * mkdir make directory * rmdir remove directory ``` c:\Program Files\Emacs>m: M:\>mkdir hello M:\>cd hello M:\hello>cd .. M:\>rmdir hello ```