As we seen most web-developer are switching to smartphone app development. Learning the new Language or switching one platform to another will take considerable amount of time , or an app has to built on multiple platforms which require lot resources + time there “Cordova” helps you.
When using the Cordova APIs, an app can be built without any native code (Java, Objective-C, etc) from the app developer. Instead, web technologies are used, and they are hosted in the app itself locally (generally not on a remote http server).
Apps using Cordova are still packaged as apps using the platform SDKs, and can be made available for installation from each device's app store.
phonegap.com use Cordova to create apps on multiple platforms. Finally a simple webapp can convert in to native app without using much resource and development time.