Is E-Trade completely free?

I'm curious, is E-Trade completely free to use for all its services? I've heard about online trading platforms offering zero-commission trades, but I'm not sure if that applies to E-Trade across the board. Are there any hidden fees or charges that I should be aware of when signing up for an account with E-Trade? It would be great to get a clear understanding of all the costs associated with using E-Trade before I make a decision.