This document discusses various types of mergers and reasons for mergers. It covers horizontal mergers between competitors, vertical mergers between companies in different production stages, and conglomerate mergers between unrelated companies. Sensible reasons for mergers include achieving economies of scale, combining complementary resources, and using surplus funds. Dubious reasons include diversification and the "bootstrap game" where a high P/E company acquires a low P/E company to temporarily boost earnings per share. The document also examines evaluating mergers based on whether there is an overall economic gain.