There are three types of signals: The methods used for each type of signal have evolved over time and fall into two broad categories: Partnerships decide on which methods to adopt and must disclose them to their opponents.
Use and interpretation is dependent upon their context, such as the contract, the auction, the opening lead or prior play, the cards visible in dummy, the cards visible in one's hand, who has led to the current trick and whether following suit or discarding.
Accordingly, partnerships generally have an order of precedence for the interpretation of signals such as that indicated in the adjacent table.
Because the declarer is entitled to know the meaning of all partnership agreements, including defenders' signals, they are also privy to the information being exchanged; this may give way to falsecarding tactics by the defenders.
With standard attitude signals one generally plays the highest card you can afford for that purpose.
With less solid holdings like QJxx(x) or KQxx(x) partner will lead with their fourth best card.
It is also possible that one have the singleton or doubleton 8, in which case declarer would have 4 or 5 cards in the suit with the bidding revealing that.
Example 1: One assumes they hold virtually all of the defensive cards, and their partner will most likely never gain the lead.
One's partner, on the other hand, knowing the situation, should consider signalling honestly.
Some partnerships (by advance agreement) signal this way only when they have a desire or ability to ruff something.
There are four common cases: Some partnerships agree in advance to play Upside Down Count and Attitude (UDCA).
Some partnerships agree in advance to assign special meaning to the first discard.
The potential disadvantage of this method is that one always have to give preference for one suit or other when one may not want any switch in particular.
This can be overcome at times by signalling for an "impossible" switch, such as a suit in which the dummy has a very strong holding such as AKQ.
The declarer is entitled to know what signaling agreements one has with one's partner, and one must disclose them if asked.
If one sees the 4, 3, and 2 in your hand, one knows that the 5 is a low club and therefore discouraging, but one should refrain from saying so.
As far as one's partner knows it might equally well be declarer who holds those cards and then you might misread the 5 as encouraging.
These signals convey a message that can only be interpreted by knowing some specifics of the hands of the defenders.