Send SMS and MMS Messages In C++` is a tutorial that guides developers on how to use the Twilio REST API to send SMS and MMS messages using C++. The guide covers setting up a Twilio account, purchasing or finding an SMS-capable number, and building a C++ application using POSIX compliant libraries such as libcurl. The code demonstrates how to instantiate a `Twilio` object with account credentials, set up libcurl for HTTP POST requests, and send messages using the `send_message` method. The tutorial provides examples of running the code from the command line and includes resources for further learning and engagement with the Twilio community.