Microsoft Edge (codename "Spartan") is a web browser developed by Microsoft and included in the company's Windows 10 operating systems, replacing Internet Explorer as the default web browser on all device classes. Microsoft says that it is designed to be a lightweight web browser with a layout engine built around web standards. The only plug-in it supports is Adobe Flash Player; it does not support ActiveX or Browser Helper Objects. It has features not supported by Microsoft's earlier Internet Explorer browsers, including integration with Cortana, annotation tools, and a reading mode. Extension support was developed and added in preview builds in March 2016, and released with the Windows 10 Anniversary Update on August 2, 2016.