WHAT IS IT?
Knitting is one of the oldest crafts developed by humanity and, along with product placement it separates us from the animals.
It is worth pointing out that there is no record of dinosaurs knitting and they all died out. Dare we at Jabberwockery suggest that their lack of knitting skills might have being the reason for this? 
It will take a while but if you stick at it long enough then you'll see the yarn or woollen thread disapeering and a functional garment appear as if by magic. 
WHERE DO YOU GET IT?
The correct equipment, including gloves, safety goggles and blasting caps may be found in a variety of different places but for those who also require a knitting guru to show them the way the average person need look no further than their nearest Grandmother 
Please note that I didn't say average Grandmother. This is because Grandmothers are awesome by default.
USING IT IN REAL LIFE:
Knitted clothes are used as birthday presents for that one child you don't really like but can't be actively seen to not actually be liking. 
USING IT IN WRITING:
Although generally seen as something that the "oldies" do it might be that your hero makes something for the love interest in your story and further plot advancement happens when that person accepts or rejects it.
Another situation might be that the world is secretly run by a ruthless cabal of knitters. The existence of the Illumiknitti could be revealed by the hero who must then step quickly in order to avoid the dark fate that awaits them at the hands of the quilted ninjas! 
MIGHT ONE CONQUER THE WORLD WITH IT?