You can learn which cards your opponents might be collecting by observing the cards they are discarding, and you can then modify your own strategy accordingly. The discard pile should be used not onlwhat is yonoy for informational purposes but also as a source of extra cards for sets & runs. You can enhance the likelihood that you will form important combinations in your hand by selecting cards from the discard pile. Picking cards up from the discard pile can provide your opponents with useful information about the cards you are collecting, so it's important to be aware of the possible risks involved.