RCS is a modern messaging standard that vastly improves on the age-old SMS and MMS technologies. It adds read receipts, a typing inductor, support for larger files, improved group chats, end-to-end encryption, and many other features to your phone’s messaging app. RCS, as you might expect, requires an internet connection to function. Even if you’re not connected to the internet, your messages will still be delivered as SMS or MMS. So your communication will not be interrupted if the internet goes down, which is something that instant messaging apps like WhatsApp and Telegram do not provide.