What does the command 'cd ..' do in a directory structure?

The command 'cd ..' is used in a command-line interface to navigate within a directory structure. Specifically, it changes the current working directory to the parent directory of the current directory. Each directory can contain subdirectories, and every directory except the root directory has a parent directory. When you use the 'cd ..' command, you effectively move one level up in the directory hierarchy, allowing you to access files or folders located at that higher level.

This understanding is crucial for navigating file systems smoothly, as it helps users manage files and directories efficiently without needing to specify full paths. The command's simplicity and effectiveness make it an integral part of command-line navigation in various operating systems.