Communication?

I have long noticed that in response to almost every relationship dilemma that appears on these forums, invariably, "communicate" is the generic and unanimous advice given, but given without explanation as to what communication really is, or how to effectively communicate. Communication is not simply talking, getting one's partner told, and/or reading him or her the riot act. Thus, my questions:

1). What is your understanding/definition of communication?

2). What might be some possible situations where talking it out is not the best option?

3). Do you agree/disagree that given some dilemmas, situations, scenarios, histories of couples, all has really been said and done?

hey look! it joey. *waves fratically* hey joey! you know im still banned...=/ *sniffle* i got over it tho. ok so what am i looking at again...?

I don't think communication always works. I think it would be annoying if someone kept nagging me to tell them everything I'm thinking about and feeling all the time.