Short rowing is a knitting technique that allows additional shaping of knitted garments. It's most often used to create bust darts but can also be used to make curved hems.
A good explanation of the concept - with photos! - can be found in Bonne Marie's short-row tutorial on knitty.com, which deconstructs the White Lies shapely tank top.
Wrapping stitches is an important part of short-rowing; it helps to avoid gaps in the fabric where the short rows begin and end. Jackie Erickson-Schweitzer's explanation of wrapping and picking up wraps is a good start.
misocrafty describes a method of using double wraps to avoid holes
Kake's method of wrapping is as follows.
To wrap: Whether on a knit or a purl row, work to the stitch before the one to be wrapped. With yarn to back, slip the next stitch purlwise. Bring yarn to front. Return the slipped stitch to the right-hand needle.
To work a wrapped stitch on a knit row: Work to stitch before wrapped stitch, slip wrapped stitch purlwise, pick up wrap knitwise with tip of left-hand needle, return slipped stitch to left-hand needle, knit wrap and wrapped stitch together.
To work a wrapped stitch on a purl row: Work to stitch before wrapped stitch, slip wrapped stitch purlwise, pick up wrap knitwise with tip of left-hand needle, return slipped stitch to left-hand needle, purl wrap and wrapped stitch together through back of loops.
Japanese short rows are an alternative way of achieving the same effect. Lucy Neatby's method seems a good one.
See Also: Knitting Tips