Oats are processed and cut into different styles to produce different textures, which can be used for different cooking processes.

1. The first type of oat that Judith identifies are steel-cut oats. These have been roughly cut with a steel knife. They take the longest of the four to cook (about 30 minutes), but they produce a lovely, rough, woodsy taste and texture. Steel-cut oats are great to use when making granola bars or granola.
2. Old-fashioned oats have been steamed and rolled. They're thinner than steel-cut oats. They're great for granolas, too, but they're also great for muffins. You want to use old-fashioned oats anytime you need a thicker consistency. They take about 15 minutes to cook.
3. Quick-cook oats are basically like old-fashioned oats, except they have been finely cut. They're great to use for oatmeal, oatmeal cookies, and any other recipes that call for a thinner consistency. Quick-cook oats are healthy, quick (as the name suggests) and very easy to make.
4. Last but not least, we have instant oats. Judith does not usually purchase these because they contain excess sugars, salts and different chemicals that have been added. They do, however, have the shortest cooking time, and can even be microwaved.