Different browsers have their own proprietary features and their own subset of the standard features implemented in their own way, bringing a lot of work for us to make these features work for all browsers.
The reason for these differences is that the W3C specifications are constantly updating, and with the constant competition among browsers, they always try promote their products as having better functionality.
However, jQuery has good cross-browser compatibility, and the flexibility to bridge some of these gaps in feature implementation across each browser. These bridges are called Polyfills.
Polyfills is the main subject of this chapter and we will also learn about: