The document describes the 5 stages of market evolution in the computing industry. It discusses the transition from vertical integration, with companies like IBM and Apple producing complete computer systems, to horizontal integration and the modularization of the industry into separate companies producing hardware and software. It then discusses how the industry further evolved into a multi-sided market through online horizontal integration and the rise of software platforms like Microsoft Windows and online networks like Google. Diagrams are used to visualize these transitions from 1-sided to multi-sided business models and the integration patterns between different players.