Software as a Service describes a solution that solves a specific problem for a specific user. And it does that repeatedly. The SaaS landscape overlaps with the B2B landscape as it is way easier to make money by writing software that solves the problems of a business than that of a direct user. Building Micro SaaS apps on top of existing large platforms is a great strategy for individual bootstrapped founders starting up on their own. Examples of great SaaS startups include Shopify and Gumroad.