This command tells you the number of characters, words, and lines in the /etc/passwd file.

wc -l /etc/passwd

This command tells you the number of lines (only) in the /etc/passwd file.

wc -w MyStory

This command counts the number of words in the file named MyStory (which can be useful if you're paid by the word!).

who | wc -l

This command counts the number of users logged into your computer system. The output of the who command is piped into the wc command, which counts the number of lines in the who output.

ps -e | wc -l

This command counts the number of processes running on your computer system.