SMS and MMS marketing notifications with Java and Servlets` is a tutorial that guides developers on how to implement an opt-in process and an administrative interface to run SMS and MMS marketing campaigns using Twilio's API and Java. The tutorial covers the building blocks of the system, including the Subscriber model, handling incoming messages, managing user subscriptions, sending notifications out, and sending SMS or MMS notifications. It also provides a closer look at how to send SMS or MMS notifications using the Twilio Message API client. The tutorial concludes by highlighting related resources and encouraging developers to check out other excellent tutorials on Java development with Twilio.