Technique
Alternate Picking
Playing with alternating downstrokes and upstrokes.
In plain English
Alternate picking uses a repeating down-up motion instead of beginning every note in the same direction. It is most often discussed by guitar and bass players using a pick.
Try or listen for this
Play four steady notes on one string using down, up, down, up, then keep that motion as you change strings.
Why it matters
An even alternating motion can make faster passages more efficient and expose differences between your downstrokes and upstrokes.