**TL;DR Vue Computed properties allow reactive data that depends on other sources, running a function whenever a dependency changes to return a new value. They enable automatic re-rendering of components when data changes, encapsulate complex logic, and improve readability. The Composition API provides an elegant solution for managing dependencies with computed properties. Here's how to use them: Create a count ref and use the computed function to create a doubleCount property that is recalculated whenever count changes. Manage multiple dependencies using the computed function, such as fullName depending on both name and age. Prevent unnecessary recalculations with the memoize function in complex applications.