Apache Cordova, formerly known as PhoneGap, is an open-source application development framework that facilitates cross-platform development by utilizing web technologies like HTML, CSS, and JavaScript. It allows developers to create mobile applications that function across various platforms without the need to write multiple codebases for each one. Cordova achieves this through a WebView component that acts as a bridge, enabling web-based applications to access native mobile capabilities via plugins. The guide highlights Cordova's advantages, such as its open-source nature, cross-platform capabilities, and cost-effectiveness, while also acknowledging drawbacks like performance concerns and limited native capabilities. The process of creating a Cordova application involves installing the Cordova CLI, adding targeted platforms, and integrating plugins to leverage native device features. Testing Cordova applications involves functional and cross-browser testing to ensure consistency and functionality across different devices and platforms. While Cordova offers a practical solution for developers with limited resources aiming to reach a broad audience, it faces challenges in performance and complexity when developing more sophisticated applications.