A coincidence lacks an apparent causal connection. A coincidence may be synchronicity, that being the experience of events that are causally unrelated, and yet their occurrence together has meaning for the person who observes them. To be counted as synchronicity, the events should be unlikely to occur together by chance, but this is questioned because there is usually a chance, no matter how small and in truly large numbers of opportunities such coincidences do happen by chance if it is only non-zero, see law of truly large numbers.