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Cardinality is a measure of the size of a [[set theory|set]].  For [[finite]] sets, its cardinality is simply the number of elements in it.

'''Cardinality''' is a measure of the size of a [[set theory|set]].  For [[finite]] sets, its cardinality is simply the number of elements in it.

For example, there are 7 days in the week (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday), so the cardinality of the set of days of the week is 7. Similarly, there are 26 letters in the [[alphabet]], so the set of letters of the alphabet has cardinality 26. As another example, the set of  suits for [[playing card]]s is 4 (there are four suits, hearts, diamonds, clubs and spades).

For example, there are 7 days in the week (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday), so the cardinality of the set of days of the week is 7. Similarly, there are 26 letters in the [[alphabet]], so the set of letters of the alphabet has cardinality 26. As another example, the set of  suits for [[playing card]]s is 4 (there are four suits, hearts, diamonds, clubs and spades).