Описание тега ie-developer-tools
For questions concerning Internet Explorer's built-in developer tools (HTML and CSS inspectors, JavaScript console, Profiler, Network Inspection, etc).
The F12 developer tools are built-in to Internet Explorer, and can be launched by pressing the F12 key.
The tools provide an HTML and CSS Inspector, JavaScript Debugger, JavaScript Console, Profiler and Network Inspector. The tool will receive a facelift in IE11, including much needed newer functionality.
Some resources on using F12 include: