I am pretty sure that most of us have drawn small curls, dots and lines on a piece of paper without actually thinking about what to draw. Filling the piece of paper without a plan, just one line or dot after the other. Some call this droodles, other say that they drew tangles. A phone call, a piece of paper and a pen. Voila, small works of art often happens while you talk. They just appear on the paper, like magic. Or you can sit in a comfy chair just letting the pen fill a paper with droodles and tangles while your mind think about something else. The repeating of patterns and shapes often help you focus. Zen.
The word is made up of Vector and Tangles. Instead of using pen and paper you use your graphic program when you draw. It can be hard to free your mind when you draw with vectors but it is doable, and you can be surprised when you look at what you have made when you look at the drawing after you have finished. If you combine a few shapes, and repeat lines in a pattern, then you also can just sit there and let the shapes flow out on that workspace allowing you to free your mind from thinking about what you do.
A Zentangle got rules, and the name is protected by the ones who started to teach this way of droodling. A droodle/tangle got no rules at all. All shapes can be a part of a tangle/droodle. Read more about Zentangles - look in the sidebar and click on the pretty graphic - visit Diane & Caroliens Weekly Zentangle Challenge.