Introduction to Agile and Scrum Framework

Scrum is a framework for developing and sustaining complex projects within which people can address complex adaptive problems, while productively and creatively delivering products of the highest possible values. Scrum is lightweight, simple to understand and pretty tough to master it.

Scrum is not a technique but the framework where you can apply different processes and techniques for building various products. So any specific strategy of scrum vary in different sources. Also, here is the link to find ways to learn about scrum.