Comes under java.util from java 1.2. before collections vector stack properties classes used to manipulate group of objects. Collections has bring these all to an unified theme and following goals. 1. High performance. Dynamic arrays, linked list, trees, hash table are high efficient. 2. Different collections must work in similar manner with high interoperability. 3. Extending and adapting must me easy. So this is built on few standard interfaces like linked list, hash set, tree set. Own implementations supported too. 4. Allowing integration of standard arrays to collections framework. Algorithms defines static methods to manipulate collections. Iterators allows standard way of accessing collection elements one at a time.(enumeration) Spliterator introduced in Java 8 to provide support for parallel iteration. It has nested interfaces to support primitive types. Jdk 5 added following to collections Genetics Auto boxing/ un boxing For each loop Generics added type safety to t