ls abbrev for list will list all the file in the current working directory 

ls -a will show all files, even the hidden files, by default files that start with a . are hidden in Linux

ls -al will show all files and provide additional information about the files such as user, owners, groups and privileges 

ls path/to/some/directory will show all the files in that directory 

Globbing.

You can use regular expressions to show certain files using ls