1, parsing HTML, DOM building
2, parse CSS, to build CSSOM
3, JS script loads
4, and the DOM CSSOM combination generating Render Tree (tree rendering)
5, the render tree traversal, the render tree of each node, and reflux redraw page, the page generating
This process is the gradual completion of the above, in order to better user experience, the rendering engine will be as early as possible to present the content on the screen, and will not wait until all the html are parsed until they have finished to build and layout render tree, it is resolve on part of the display part, while the rest may also download content over a network.