Weaving in ends?

How do you weave in an end and when do you use it?

Whenever you have a ‘tail’ of yarn, usually from attaching a new ball or a new color, you need to weave it in to the back of your work so it’s not hanging there, usually by putting it on a tapestry needle and sewing it under the stitches on the back in the most unobtrusive way possible. On scarves, I usually weave it down the sides–shows less that way.