Wood burning involves using a hot, pen-like brass pen to "draw" onto a surface made of wood, leather, woven straw or cork. The contact of the hot tip of the pen with the surface "singes" it.
The area touched by the hot tip of the pen is dyed (burned) a dark brown to black colour by the heat of the tool. The colour intensity of the mark depends on how long the tip of the branding pen remains on the surface and is a feature of this unusual drawing technique.
It can be compared with glass engraving, where images are made out of lines and dots spaced closely or far apart.
There are different tools to make your drawing: the most important are the drawing and writing tips which you can use to make narrow or wide lines without using a lot of pressure.