Tracked properties are one of the most exciting features introduced in Ember Octane, and they represent a shift in the model for state management in modern Ember apps. But what makes a property "tracked"? Why do we have to decorate our properties? And how does this all differ from how other web frameworks think about state? In this deep dive talk, I'll discuss the problems of state management and reactivity, and a number of solutions that have evolved over the years. I'll also show the internals of autotracking, and demonstrate some the unique benefits it gives to developers!