Crochet thread (also known as lace yarn or fingering yarn) is the lightest-weight yarn used to knit or crochet. Popular for lacy projects such as shawls and doilies, crochet thread is generally 100% cotton, though there are some brands that blend a bit of metallic with the thread.
Size 10 crochet thread, known in the Aunt Lydia’s Crochet Thread brand as Classic 10 is the most popular size, though it also comes in other sizes such as Fashion 3 size, Perle 5 size, and Fine 20 size crochet thread. Crochet thread is sold in balls, cones, or in color-coordinated value packs.