Metaprogramming in JavaScript is significantly enhanced by the use of proxies, a feature introduced with ECMAScript 2015 (ES6), which allows developers to redefine fundamental object operations for various practical applications like access control, caching, data binding, and logging. Proxies provide a way to create powerful, virtualized objects by substituting for a target and handling operations through traps. This guide explores multiple use cases such as using proxies to implement tracing for debugging, achieving two-way data binding, and creating memoized functions to optimize performance by caching results. Additionally, proxies can control access to objects by validating inputs, offering read-only views, and simulating private properties. While proxies offer versatile solutions in metaprogramming, they are not recommended for performance-intensive tasks, necessitating thorough testing to avoid potential drawbacks.