There are different kinds of mobile phones in the market these days. The platform or operating system that are used in a phone are iOS, Android, Blackberry, Windows, etc. Developers tends to choose a platform that helps them to develop the applications in one common language that would be supported by all the popular platforms. This is called as the cross platform mobile development.
Phonegap or Cordova is one of cross-platform technology which can be used in most devices & platforms by writing a minimal amount of source code. There are many advantages if we take up this approach.