A lanyard is essentially just a piece of string that you wear like a necklace that has hooks and or rings that you can use to attach all your accessories to. Some swear by using a lanyard: it's simple, lightweight and enables you to have all your gear right in front of you.
The lanyard shown above from Loon Outdoors can be found here: https://loonoutdoors.com/products/neckvest-lanyard
Want to read more about fly fishing accessories? Check out our list of the essential fly fishing accessories.