What does the android sdk really do? and is it really important?

i have an android phone and i see alot of things on the interenet about android sdk but i dont really know whats its for and if its really important for my phone plz answer A.S.A.P!!!! THX|||an sdk is a software development kit. you don't need (or even want) it unless you know how to program and want to make applications for android.|||It's for making Android apps. If you don't want to make apps for Android, don't bother with it.