The function of the c-bet is to confirm that you believe you have the best hand. You first did that with a preflop raise, and now post flop, you don't want to give anyone the impression your hand has gone belly up. So you c-bet almost any flop which re-enforces the notion that you have a big pair, or hit the flop good
Im not sure I agrre with thatstatement dj11.
The accepted use of the c-bet is to declare that you have a hand that has connected with the flop or was premium preflop and the flop hasnt changed that. (which is what you said)
However, since beginning to learn about poker (and I admit I am an absolute beginner) I have seen a lot of advice advocating the use of the c-bet regardless of hitting the flop or not.
In fact its often given by pros etc on youtube stuff I have seen as an inside tip.
I think a while ago it was used to declare a hand, and had a secondary use as a bluffing tactic.
But this advice is now so mainstream that most players c-bet regardless of the flop. It is done in position and is effectively the flop's unofficial blind.
I believe its usage has evolved. It is simply a defence against weak / passive players and short stacks. The pre-flop bet probably declares a reasonable hand.. but the c-bet is now simply an extension of that initial raise. Its almost meaningless. Except to weak players who called the flop with nothing, it causes them to give up the pot. Shortstacks who havnt hit the flop are also put in a position where they realise they probably cant steal pots. Against a strong player, and with a competative chip stack, would you fear his c-bet?
I wouldnt, in fact its so routine that I would be expecting to pay it anyway.