music in video is from demo 2008 by (Latch\xe9 Swing) / CC BY-NC-SA 2.0
This video knitting tutorial will help you learn how to knit through the back loop. This technique is used to twist your stitches and is often done in decreases. It can also be used to great effect to create a wavy fabric as an alternative to stockinette.
Insert your working needle into the stitch purl wise, exiting through the backside of the stitch. Then wrap your yarn and pull through the stitch as if knitting normally.
Example of stockinette knit through the back loop
Example of Twisted Stockinette (top) and regular stockinette (bottom)