Map stores key-value pairs, where each key is unique. HashMap, TreeMap, and LinkedHashMap are implementations of the Map interface.
Source Code
Map map = new HashMap();
map.put("Alice", 30);
map.put("Bob", 25);
System.out.println(map.get("Alice")); // Outputs "30"
Use Map when you need efficient lookups/searches by keys and to store key-value associations.