With the rising popularity of single page applications, mobile applications, and RESTful API services, the way web developers write back-end code has changed significantly. With technologies like AngularJS and BackboneJS, we are no longer spending much time building markup, instead we are building APIs that our front-end applications consume. Our back-end is more about business logic and data, while presentation logic is moved exclusively to the front-end or mobile applications. These changes have led to new ways of implementing authentication in modern applications.