Nalbinding is the process of continually sewing a series of loose knots to make a fabric for any number of items from socks and mittens to dresses. Though many people think of it as a northern European art; as a skill, nalbinding has been dated back at least as early as 4th century Egypt, .
There are several beauties to this craft. The first is that it only requires a single blunt needle and yarn to make a project. The second is; though a bit more time consuming than knitting, a dropped stitch does not result in the unraveling of the work. There are also a number of stitch techniques which result in a variety of textures.
The York stitch presented in this video by Petra (www.youtube.com/user/pittyom) is a reasonably basic technique. It is frequently attributed to what is believed to be a 10th century sock made with the stitch discovered at the Coppergate dig in Jorvik/York, England. The stitch is diagrammed using what is known using Hansen’s classification as UU/OOO. In other words under under / over over over. The F1 and F2 as explained by Petra in the video is a reference to the method of connecting to the next row.
An image of the Coppergate sock can be found through the York Archaeological Trust at http://www.jorvik-viking-centre.co.uk/gallery/