WebVR is a Mozilla-driven standard that describes the implementation of VR applications in a browser. Official specs are available on the W3C website https://w3c.github.io/webvr/
The WebVR is obviously based on WebGl. The goal is to share VR content for all, regardless of the browser and whatever the helmet used, or even directly on a computer screen in a 360 view if you do not have a headset available.
As today browsers have their specificities on the js or the html, it is necessary to take care to manage all the types of devices and their possible interactions if one wants to offer the richest experience (for example to manage the peripherals which represent the hands on the oculus). Each web browser also exposes more or less methods to access these devices (the Samsung browser is better to handle the helmet gear for example).
There are some frameworks to facilitate the development of WebVR applications. The best is today A-frame, pushed also by Mozilla. It has many basic components while remaining highly customizable.
More recently, Amazon offers Amazon Sumerian in beta developers. This tool offers a development interface similar to that of Unity, and will exploit the full potential of the Web VR. A project to follow.
For which applications ?
The possibilities are endless, the limit is your imagination. From the educational application on the human body, to the discovery of space through the horror game, everything is possible. You will find here some use cases :
Coupled with augmented reality ?
There are other augmented reality frameworks like AR.js, which combined with VR offer even more crazy perspectives, as you can seen in this example :
WebVR brings virtual reality to all in browsers. Everything is to be done in this area, and new professions of VR space designers will certainly be created. This step of the WebVR is the beginning of a web version more tactile, more intuitive, and more interactive.