The reactivity system introduced in Owl 2 is a powerful primitive that empowers application developers by allowing them to write code in a simple and straightfoward manner and update the UI with no fuss. In this talk, we will give a a brief technical overview of how this system is implemented, go over its key features, and discuss how it stacks up with other approaches in the Javascript ecosystem, such as Vue, React, Svelte and Solid. We will also discuss how leaning into the reactivity can make code much simpler and enable a single change to update various parts of the UI seamlessly.