This is "board". A WebApp that allows to overlay writing and drawing over other WebApps or pages.
The top bar is the tool bar that you use to draw or write with the mouse or a pen device. The frame bellow it is where the page and/or WebApp is displayed. To start drawing in the board, click in the "draw" button, than, click and drag the mouse over the board. You can also pick the colors, line width or eraser in the tool bar.
Click on "APP" to open a web page or any of the pre selected WebApps. Once the page or the WebApp opens in the frame, you can start using it normally. To overlay your drawing or writing, just click "draw" the start doodling. The system will overlay the strokes on top of the page, as if there was a glass between the board and the page. To go back using the page, click on the "use page" button (where there was the "draw" button). Now you can go back to use the page.
When drawing with the board, you can scroll up or down with the mouse wheel to access more blank board infinitely (on both directions, up and down). This allows you to continuously draw or write without having to clear the page and loose what you wrote or drawn before.
All the strokes are vectors. Although you can erase part of a stroke, the system will split the stroke as necessary. This allows you to select individual strokes, copy and past even if they overlap with other strokes.

Click OK bellow to see details of the other buttons and learn about other functionalities.