In Bridge, silence can sometimes be golden. Although we are expected to bid our values whenever opportunity arises, if does not always give dividends, rather it is the other way around. For with the information divulged the opposing side, particularly the declarer can take a favorable inferential clue towards making his bid contract.
Let us learn by examples. In our first example, NS reach a contract of 3NT on the following hands with the bidding given below, north south being vulnerable with the declarer being west who opens the bidding with 1D.

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North
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K 10 5
K 9 7 5
J 4 2
J 7 3
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South
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A Q 4
A 2
K 10 7 5
A Q 6 4
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The bidding continues with:

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W    N     E         S
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1D   P     P       Dbl
P    1H    P       2NT
P    3NT      All pass
======================

West opens the proceeding with the 3H. Place yourself in the south seat and plan your contract as best as you can for on the face of it with 27 combined HCPs and 3 stoppers in every suit, the contract could be plain sailing. Counting your winners you can see 3 in spades, 2 in hearts, 2 in clubs and most likely two in diamonds with the extra chances of third club and diamonds in case clubs and diamonds break 3 - 3.
So how do you go about it. Suppose you play low from dummy and east's 8 draws your AH. The hearts now look rather fragile. Well you know you have to try the clubs placing KC with west. So at tricks 2 you cash AC and play low to the KC with west. West now clears the hearts which you duck once only to find that west had led low from a holding of QJ103.
The situation looks grim with only 7 tricks in sight - 3 in spades, 2 in hearts and 2 in clubs. With diamonds quite open, south can hardly expect, the top honours in diamonds to be split knowing that west opened the bidding with 1D. 2 Diamond tricks with west plans his KC spells doom for the declarer. Can you find the better line for making 3NT?
Well, the contract can be redeemed, if declarer cashes his 6 winners in spades and clubs to exit with a heart and let west score his heart trick. Thrown in, west is end played with his original holding being:

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9 3 2
Q J 10 3
A Q 8 6
K 8
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Left with only diamonds west has to concede a diamond trick to the declarer for his 9th trick and the contract; west's bidding gave south the path to make 3NT.
Our next illustration has NS reaching a 4S contract after west has overcalled with 2C on south's 1S opening with the following hand:

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North
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A 10 8 6
K J 7 5
8 7 3
A J
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South
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K Q 9 7 4 3
A 6 3
K 6 4
8
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West's opening lead is the KC. As south how do you intend to make 4S with diamonds fully exposed? At first sight it looks as if you have no choice but to hope for the heart finesse of the Q to be right for you for otherwise you are giving away 4 tricks to go one down.
But Bridge offers alternates that can give the additional chance of making the contract even if the obvious (and what seemed at first the only) line was failing. Can you spot the winning line?
This is one contract where the opening lead has given the declarer an inspiration to find the winning line. Any ideas now? Yes, the winning line can be to take the KC with the AC, draw trumps; cash the AH and the KH and continue with the JC from dummy discarding the third heart from hand west is now kaput - end played. A diamond would give south his KD. A club would concede a ruff and discard. If west has a heart or 2 left his lead of heart would not help him either. Declarer's JH would either win or if east produces QH to be ruffed, dummy's last heart would triumph, if suit is breaking 3-3. In both illustrations, declarers succeeded keeping the bidding in mind.