PhoneGap is an open source framework that allows developers to create mobile apps using standard web technologies like HTML, CSS, and JavaScript. It works by wrapping web content in a native container so it can access native device capabilities like the camera or accelerometer. PhoneGap supports major mobile platforms and its APIs allow apps to access native functionality while maintaining cross-platform code. While PhoneGap apps have a web-like interface, libraries like KnockoutJS can help achieve native-like UIs. PhoneGap is a viable option for cross-platform development when budgets are low and code reuse across platforms is important.