What is HomeKit app? And as an iPhone user, do you i need it?

You will find a good answer here..

http://www.apple.com/in/ios/homekit/

http://www.imore.com/homekit

Overall this is to control your home accessorieslike fan,lights etc from your iPhone. 

HomeKit is apple apple store collection of app, and specific HomeKit-enabled accessories. are compatible with this, you can control these accessories through

 u r iphone   

I don't know because I'm using Android based phone 

Thanks for invitation 

Sorry I'm using Android based phone