nova launcher?

[CamDroid8]

I've been hearing from people to get nova launcher. What is that and is it something to help battery life and lag or what? And do you guys prefer it ?

 

[fcmatteo]

A launcher is like the "desktop" of your device. Like a theme but not only about the appearance. It can make your phone home screen nicer, improve the performance and help with battery life, but it could have the opposite effect too. That's what I understand, if it's wrong please anybody correct me.
I haven't used Nova, but it's one of the most recommended launcher.