Yarn weight refers to the thickness of the yarn, which affects how it is used in knitting or crocheting. It is categorized into different groups, such as lace, fingering, sport, worsted, and bulky. Each category has a specific range of thickness, influencing the final appearance and texture of the finished project. Choosing the right yarn weight is essential for achieving the desired outcome in your work. Patterns often specify a particular yarn weight to ensure proper gauge, which is the number of stitches per inch. Using the correct weight helps maintain the intended size and drape of the item being created.