The workhorse of yarn weights - this is the go to for so many projects. 

Worsted weight yarn is a medium weight yarn, between a DK/Sport weight and a chunky weight yarn. Commonly used for sweaters, scarves, hats and light blankets, it's also a great beginner yarn, where thinner and bulkier yarns can be more of a challenge. Also popular with crochet where it is often made into blankets and throws.

Needle size for worsted weight projects can vary based on desired effect so check your pattern for recommended needle size.

Also consider the number of plies your worsted yarn has, with more plies giving more strength and durablity, meaning less pilling. So for hats and gloves/mittens especially look for a multi ply worsted like Jade Sapphire's Zageo.