Many people use hybrids on long fairway shots as they allow better accuracy than fairway woods. This is because they are slightly shorter in length, and therefore much easier to control, even with a heavy steel shaft.
Additionally, hybrids can hit a ball from fairways and the rough as well as an iron, and are easier to hit than woods. Like many of the drivers available, some hybrids have adopted strategic weighting to benefit slicers and hookers.
As well as being excellent replacements for the low and mid irons, hybrid clubs are often used as chipping clubs around the green.
With a low profile sole, they allow a greater margin of error (forgiveness) than irons and wedges, and minimise the chance of hitting the ball terribly (duffing). Todd Hamilton capitalised on this using his hybrid to beat the competition in the 2004 Open Championship, chipping consistently with it.