Association

Association[key1 -> val1, key2 -> val2, ...] or <|key1 -> val1, key2 -> val2, ...|> represents an association between keys and values.

Examples

Create an association:

assoc = <|"a" -> 1, "b" -> 2, "c" -> 3|>

Access values by key:

assoc["b"]
(* 2 *)

Get all keys or values:

Keys[assoc]
(* {"a", "b", "c"} *)

Values[assoc]
(* {1, 2, 3} *)

Please visit the official Wolfram Language Reference for more details.