The throwing line can be defined as a line on the floor you must never cross, or at least while throwing darts. You can either simply draw a line on the floor, use a tape to mark it or place a raised bar made of wood. If you opt for the bar, you should know that it is known as the "oche" or "hockey" and that it should be around one inch high and two feet long (or more). In my opinion, oche is the better option as it actually blocks the foot of the player and makes the overstepping incidents inexistent. That eliminates a lot of arguments, believe me!