In the sweater world, the very basic "building block" is the jersey stitch. It is a single knit struture that is used in sweaters & knit fabrics. Even if you don't know what it is called, most of sweaters & T-shirts are made in this stitch. The jersey stitch is made where each loop is drawn through other loops to the right side, giving the sweater a flat structure. The back side of the jersey stitch is commonly called reversed jersey.
Image of Jersey Stitch
Image of Reversed Jersey Stitch