I have always thought that Aleinu was a piyyut (liturgical poem), not a "prayer" since it does not have a bracha in it. I was surprised to find that the Wikipedia page for piyyut does not list it, and that the page for Aleinu calls it a prayer. I realize that Wikipedia may not be the most authoritative source for Jewish answers, so I am asking it here. Is Aleinu considered a piyyut or a prayer? Either way, why? A related (unanswered) question is: Why are Ashre and Alenu considered communal prayers?