Most large-scale web companies have evolved their system architecture from a monolithic application and monolithic database to a set of loosely coupled microservices. Using examples from Google, eBay, and other large-scale sites, this talk outlines the pros and cons of these different stages of evolution, and makes practical suggestions about when and how other organizations should consider migrating to microservices. It concludes with some more advanced implications of a microservices architecture, including SLAs, cost-allocation, and vendor-customer relationships within the organization.