Ball Band
The ball band is the paper label around a skein of yarn that lists key information like yardage, fiber content, recommended needle size, and gauge.
Explanation
The ball band is the label that comes with every skein of yarn, containing information you need to plan a project: total weight and yardage, fiber content, recommended needle size, stated gauge, washing instructions, and color/dye lot number. The dye lot number is especially important to note, since yarn dyed in different batches can have subtle color variations. It's worth keeping at least one ball band per project for reordering or mending later.