Yarns have labels that provide lots of information about the yarn you have selected, such as the type of yarn it is, the amount or yardage in the ball or skein, fiber content, care instructions and recommended needles or hook to obtain the gauge. On the label you will also see reference to yarn color names, numbers or dye lots. If a yarn has a dye lot number, it is always recommended that you purchase enough of the same dye lot to finish a project because there can be subtle color differences in yarns dyed in different batches. Increasingly, many yarns will say "No Dye Lot Yarn" which means the fibers were dyed prior to being spun so there should be no color differences. Many labels also include free patterns.