Tunisian crochet is known by several names. You will find it referred to as afghan crochet and tricot crochet. It differs from standard crochet as it is made by using a long crochet hook with a stopper at one end that looks like the head of a knitting needle. This form of crochet was popular early in the twentieth century.
Articles online that cover this form or crochet include Tunisian Crochet : Tapestries in Cross Stitch & Embroidery