My iPhone is not backing up (why)

Hi stephaney161,

Welcome to Apple Support Communities. Since you recently reviewed What does iCloud back up? - Apple Support, it seems that you are referring to an iCloud backup. Right?

What happens when you try to create an iCloud backup from Settings > [Your name] > iCloud > iCloud Backup > Back Up Now? For instance, you might encounter a message about backup or a general error message. Depending on the message you receive, reference the corresponding section of If you can't back up to iCloud - Apple Support and give those steps a try.

Take care.