What is tatting?

So a friend of mine suggested I write a post explaining what tatting is. So here is a basic explanation.
Tatting is a type of knotted lace. It is made by making double stitches over and over in either a ring or a chain. The double stitch is comprised of two parts and is basically a half hitch knot. There are a variety of styles used to tat, with the most common being shuttle tatting and needle tatting. The style I use is shuttle tatting.

A bobbin shuttle, tatting a size 30 white butterfly

To make a chain, you use two threads: the shuttle thread and a ball thread. While to make a ring, you only use the shuttle thread.

Purple thread is a ring, while blue is a chain

I won't go into detailed instructions on how to tat, as other tatting blogs have already posted clear, easy to follow written instructions and videos. One such blog is Tatted Treasures, so if you are interested in learning to tat I would suggest looking there at her Absolute Beginner series.