Spring is a powerful open-source, loosely coupled, lightweight, java framework meant for reducing the complexity of developing enterprise-level applications. This framework is also called the “framework of frameworks” as spring provides support to various other important frameworks like JSF, Hibernate, Structs, EJB, etc.

There are around 20 modules which are generalized into the following types:

Core Container

Data Access/Integration

Web

AOP (Aspect Oriented Programming)

Instrumentation

Messaging

Test