The new iOS 10 has a lot of features, one of my favorites is the Notes Collaboration. You can set this up by creating a note and tapping on the collaboration icon, which is circled in red in this screenshot.
After you tap on that icon, you can choose how you would like to send your Notes collaboration invitation whether it is through Text, Facebook post or message, Email, Twitter, WhatsApp, etc. (For this to work your Notes must be connected to your iCloud). Once connected you and the other person will be able to update the same note until you remove their access. You can remove their access by tapping on the collaboration icon again.
