In the context of iOS 18, RCS refers to Rich Communication Services. It is an evolved messaging protocol intended to replace SMS (Short Message Service) and MMS (Multimedia Messaging Service) with a more feature-rich and modern experience. RCS provides capabilities such as read receipts, typing indicators, high-resolution image and video sharing, and group chats with enhanced functionality.
The adoption of this protocol by Apple in iOS 18 signals a significant shift towards interoperability in mobile messaging. Historically, the messaging landscape has been fragmented, with different platforms utilizing proprietary systems. This advancement aims to improve the overall user experience by offering a more unified and capable messaging system across different operating systems, closing the feature gap that previously existed between iMessage and other messaging services.