Actually, it is just a word to describe the property that if you do something repeatedly, it leads to the same result as doing it just once. So the latter execu

Actually, it is just a word to describe the property that if you do something repeatedly, it leads to the same result as doing it just once. So the latter executions don't change anything. And because it is such a common property when talking about algorithms and APIs the word is pretty common among CS people. One very popular example are REST APIs because some HTTP verbs are idempotent and others are not [1]. This is also the reason why your browser asks you, if you want to submit a form again when refreshing a page that has been reached by submitting a POST-form. [1] https://en.wikipedia.org/wiki/Representational_state_transfer#Semantics_of_HTTP_methods https://en.wikipedia.org/wiki/Representational_state_transfe...