Purl Front & Back (pfb, pf&b, or p1f&b) and pfbf (or pf&b&f)
Purl front and back (pfb, pf&b, or p1f&b) is a one-stitch purlwise increase usually done on the wrong side of the fabric, but sometimes done on the right side. The purl front, back & front (pfbf or pf&b&f) is a 2-stitch purlwise increase also usually done on the wrong side.