What stitch makes knitting elastic?

Knitting can be made more elastic by using stretchy stitches such as ribbing. Ribbing is typically 1x1 or 2x2, but many other types of ribbing are possible, and many non-ribbing stitches are also stretchy.

1x1 ribbing is formed by knitting one stitch and purling the next. Repeat these two stitches to the end of the row. On following rows, "knit the knits and purl the purls." This simply means you should look at the stitch you are about to work and determine whether it looks like a knit or like a purl. Remember that a purl is simply the back side of a knit stitch. Knit stitches look like the letter "V," while purl stitches look like dashes ("-").

2x2 ribbing is very similar to 1x1 ribbing except that you knit two stitches and purl the next two stitches. Again repeat to the end of the row, and again "knit the knits and purl the purls."