Vue.js, a popular JavaScript framework for building single-page applications and UIs, offers the app.config.globalProperties feature in Vue 3, allowing developers to access properties and methods globally across an application. This guide explores the transition from Vue.prototype to app.config.globalProperties, enabling the addition of custom properties and methods to Vue instances, thereby reducing the need for repetitive imports. By illustrating how to set up a new Vue 3 project, the guide demonstrates the application of global properties through examples such as reversing strings and incorporating third-party libraries like Axios for HTTP requests. The use of global properties streamlines workflows by making functionalities accessible throughout the application, enhancing efficiency without the need for repeated code.