Designed by Evan You and released in 2014, the framework is a direct response to You’s time spent working with AngularJS at Google. You wanted to extract the bits and pieces he liked from AngularJS and create an entirely new but notably lightweight framework.
The MVVM architecture allows for the business logic, or model, to be distinguished from the graphical UI, or view.
In effect, the distinction provides an intentionally intuitive pattern for front-end and back-end developers to work with. The viewmodel is the structure keeping such concerns separate, acting as a liaison.