Message passing, and pattern-matching on the message structures. Learning to use message-passing idiomatically is a huge part of programming Erlang. Erlang is

Message passing, and pattern-matching on the message structures. Learning to use message-passing idiomatically is a huge part of programming Erlang. Erlang is arguably more OOP (in Alan Kay's sense) than something like Java or C++, as it more directly implements late binding and message-passing.