WebKit is a layout engine software component for rendering web pages in web browsers. It powers Apple’s Safari web browser, and a fork of the project is used by Google’s Chrome web browser. By September 2013, WebKit browser market share was larger than that of both the Trident engine used by Internet Explorer and the Gecko engine used by Firefox. WebKit also forms the basis for the experimental browser included with the Amazon Kindle e-book reader, as well as the default browser in the Apple iOS, BlackBerry Browser in OS 6 and above, and Tizen mobile operating systems. WebKit’s C++ application programming interface provides a set of classes to display web content in windows, and implements browser features such as following links when clicked by the user, managing a back-forward list, and managing a history of pages recently visited. WebKit’s HTML and JavaScript code was originally a fork of the KHTML and KJS libraries from KDE, and has now been further developed by individuals from KDE, Apple, Google, Nokia, Bitstream, BlackBerry, Igalia, and others. OS X, Windows, Linux, and some other Unix-like operating systems are supported by the project. On April 3, 2013, Google announced that it had forked WebCore, a component of WebKit, to be used in future versions of Google Chrome and the Opera web browser, under the name Blink. WebKit is available under a BSD-form license with the exception of the WebCore and JavaScriptCore components, which are available under the GNU Lesser General Public License. As of March 7, 2013, WebKit is a trademark of Apple, registered with the U.S. Patent and Trademark Office.