The book "Programming Interactivity" describes the next stage in the evolution of interaction design. In addition to user experience, it regards the complete user economy with an emphasis on the social and entrepreneurial aspect. Most notably, instead of low- and hi-fidelity interactive prototypes, it encourages the lean development of interactive minimum viable products (MVP). Finally, besides user interaction with a particular device, the book advocates a focus on interaction with an ecosystem of users, devices, and services. The book has been carefully edited in order to avoid computer jargon and technological fads, so, despite the title ("programming"), you will not find a single line of computer code in the text, which is also complemented with beautiful interlude images from timely interactive systems. Moreover, the book has been deliberately produced to be coherent (average reading time should be less than 5h) and all extra material appears in a complementary web site: http: //mibook.org/gr