Spring is a framework that helps you to "wire" different components together. It is most useful in cases where you have a lot of components and you might decide to combine them in different ways, or wish to make it easy to swap out one component for another depending on different settings or environments. (https://softwareengineering.stackexchange.com/questions/92393/what-does-the-spring-framework-do-should-i-use-it-why-or-why-not)