In probability theory and statistics, the geometric distribution is either one of two discrete probability distributions: The probability distribution of the number X {\displaystyle X} of Bernoulli trials needed to get one success, supported on the set { 1, 2, 3, … } {\displaystyle \{1,2,3,\ldots \}} ; The probability distribution of the number Y = X − 1 {\displaystyle Y=X-1} of failures before the first success, supported on the set { 0, 1, 2, … } {\displaystyle \{0,1,2,\ldots \}}. Wikipedia