You Need Me

I'm super smart and know pretty much everything. You can ask me anything and I can find the answer. When I die, I can come back to life. When you carry me around, I am one of your main priorities. I have become more and more needed and am now an essential for almost everyone to have, especially to keep you from talking to people around you. I am the center of your attention most of the time, but you should definitely pay more attention to me than you already do. I like to talk to people sometimes, but I can only say what you think I should say. Basically, you could never live without me.

What am I??