What is meant by draw advantage in horseracing?

In Flat racing, each horse is allocated a starting stall. Depending on the course, distance, ground conditions and number of runners, some starting positions may offer an advantage over others.

At Ascot, for example, the effect of the draw can vary between the straight and round courses. A favourable draw may allow a horse to obtain a better racing position or avoid covering unnecessary ground. However, there is no guarantee that a particular stall will produce the winner.