[scribu]

Erlang/Elixir noob here. Are you saying that protocols are a useful thing to learn in a) Erlang, b) Elixir or c) both?

[phamilton]

Protocols (and macros) are the real differences in Elixir that you don't have in Erlang.

The presence of protocols in Elixir enable many really cool features and designs that you wouldn't be able to do easily in Erlang.

[gargantuan]

Elixir has them built-in. They are basically an interface. A protocol says "this object implements this interface".