The root directory is the top-level directory of a computer's file system. It typically contains all other directories, files, and subdirectories. In order to access the root directory, you will need administrative privileges on your computer and the appropriate software installed. On the latest version of macOS, you can access the root directory by opening the Terminal and entering the "sudo -s" command, which will give you superuser access. On Windows, you can access the root directory by opening the Command Prompt as an administrator and navigating to the "C:\\" drive. However, it is important to note that modifying or deleting files in the root directory could potentially harm your computer or operating system, so it should always be approached with caution.