Spring is a powerful framework that solves many common problems in J2EE. Many Spring features are also usable in a wide range of Java environments, beyond classic J2EE.
Spring provides a consistent way of managing business objects and encourages good practices such as programming to interfaces, rather than classes. The architectural basis of Spring is an Inversion of Control container based around the use of JavaBean properties. However, this is only part of the overall picture: Spring is unique in that it uses its IoC container as the basic building block in a comprehensive solution that addresses all architectural tiers.
Spring provides a unique data access abstraction, including a simple and productive JDBC framework that greatly improves productivity and reduces the likelihood of errors. Spring's data access architecture also integrates with TopLink, Hibernate, JDO and other O/R mapping solutions.
Spring also provides a unique transaction management abstraction, which enables a consistent programming model over a variety of underlying transaction technologies, such as JTA or JDBC.
Spring provides an AOP framework written in standard Java, which provides declarative transaction management and other enterprise services to be applied to POJOs or - if you wish - the ability to implement your own custom aspects. This framework is powerful enough to enable many applications to dispense with the complexity of EJB, while enjoying key services traditionally associated with EJB.
Spring also provides a powerful and flexible MVC web framework that is integrated into the overall IoC container.
