What is the Java Collections Framework?

The Java Collections Framework (JCF) is a unified architecture of interfaces, implementations, and algorithms for working with groups of objects. The core interfaces are Collection (the root), List (ordered, allows duplicates), Set (no duplicates), Queue (FIFO ordering), and Map (key-value pairs, not a true Collection). Common implementations include ArrayList, LinkedList, HashSet, TreeSet, HashMap, TreeMap, and PriorityQueue. The utility class Collections provides static methods for sorting, searching, reversing, and synchronizing collections. Always program to the interface, not the implementation: List<String> list = new ArrayList<>();.