Knitting
Knitting uses a pair of needles to transform a long ball of thread into a tightly-looped fabric that is flexible and warm.
Knitting probably originated in the Egyptian region (maybe around the 11th or 12th century) and slowly began to spread across Europe in around the 14th century. It took a lot longer to reach further away places like England and Scandinavia.
Knitting-like techniques
Naalbinding could easily be mistaken for knitting if you've never done it - the technique actually uses a needle and short lengths of thread to create the thickly looped fabric. http://www.stringpage.com/old/basicnaal.html
Sprang creates a stretchy netting like texture, which in some circumstaces and weaving patterns could be mistaken for knitting.
Many old books will label naalbinding as knitting, so be very cautious using old books to prove early use of knitting.
Using knitting
You can knit all sorts of great stuff for winter for the SCA, such as scoggers and socks.
For the less authenticity inclined, knitting can be used in substitute for naalbinding for early period personas (eg socks, shoe liners, and mittens for Vikings, hose, stockings and gloves for 12th C Germans).
By the 16th Century items such as knitted stockings have been found, for example Queen Elizabeth famously owned a pair of knitted stockings.
