Solved Puzzled with Google email account..

Please help me, Do I have to provide my gmail login credentials to all those apps in my phone (Gmail, Google, Chrome, Internet)... or they just compete with each other? I just want one mailer (say Gmail) to sync up... So far I get weird messages like "sync error" or most annoying "wrong password, please type-in correct password" and I'm really fed up with. Could someone tell me in plain English what's going on? (or at least give me an appropriate link...) Thx

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