What are common `ls` options?

Common ls options include:

1. -a: Lists all files, including hidden files (those starting with a dot).
2. -l: Displays detailed information about files and directories in a long format.
3. -h: Shows file sizes in a human-readable format (e.g., KB, MB).
4. -R: Lists subdirectories recursively, showing their contents as well.
5. -S: Sorts files by size, largest first.
6. -t: Sorts files by modification time, with the newest first.
7. -r: Reverses the order of the sort.
8. -X: Sorts files alphabetically by file extension.
9. -1: Lists one file per line.

You can combine these options for more customized output, such as ls -alh to show all files with detailed information and human-readable sizes.