Event-sourcing has been around for a long time. When humans first created money thousands of years ago, accountants invented the earliest forms of event-sourcing when they realized it was not a good idea to throw away data while keeping track of other people's money. Fast forward to today, accountants continue to use event-sourcing. It may surprise some developers, but event-sourcing is a crucial component of the software development process in the form of git.  A more general form of event-sourcing for data other than financial data was introduced around 2007 by Greg Young. While the event-sourcing concepts are solid, based on thousands of years of experience, the adoption by the development community has been slow. In this session, we will look at event-sourcing from a perspective as an indispensable component of modern, distributed, cloud-based microservice systems. We will also examine why event-sourcing adoption has been slow and why things are changing, making it easier to include event-sourcing in your microservice systems.