Twist is put into the yarn prior to carpet tufting.  In general, the more turns per inch, the tighter the twist, the less bulk in the carpet, but the better the carpet’s performance.  Twisting allows the tuft to keep its shape and stand straight.  One way to judge the twists levels of various samples is to look closely at the cut tips of the individual tufts.  They should be neat and well defined rather than flared open.