An OCaml list is a sequence of values all of which have the same type. They are implemented as singly-linked lists. These lists enjoy a first-class status in the language: there is special support for easily creating and working with lists. That's a characteristic that OCaml shares with many other functional languages. Mainstream imperative languages, like Python, have such support these days too. Maybe that's because programmers find it so pleasant to work directly with lists as a first-class part of the language, rather than having to go through a library (as in C and Java).