Flat paint, also sometimes called matte paint, is paint that dries to a minimally reflective finish. There are both advantages and disadvantages to using this type of paint, which must be considered when picking out a product to buy. Alternatives include satin, eggshell, semi-gloss, and gloss paints, all of which have varying degrees of reflectivity, with gloss paints being the most reflective.
One of the biggest advantages to flat paint is that it adheres readily, taking to rough surfaces very easily. This is also a disadvantage, however, because it will tend to grip dirt and stains. This paint is much harder to clean than glossier paints, which is why people often recommend that it is used on locations like ceilings, which do not usually attract stains. It definitely needs to be avoided in high traffic areas like kitchens, where it will soak up grease, dust, and dirt and look very unsightly.
This type of paint also tends to hide rough surfaces. A glossy paint will highlight every pit, crack, and crater in the surface it covers, making a wall look far worse than it actually is. Matte paints, on the other hand, will tend to minimize rough surfaces, because they don't reflect the light from every angle of every divot and rise in the underlying wall. For this reason, one may be used when people paint over textured walls with the goal of minimizing the appearance of the texture.
In addition to being used in houses, flat paint is also sometimes used to paint cars, although it is important to distinguish between a paint job of this type and a primer. Auto primer, like other paint primers, is flat because it is designed to cover the vehicle and provide a rough surface for another layer of paint to adhere to. Glossy paints don't work as primers because the next layer of paint will slide off. Primers do not provide all of the protection that true finish paints are designed for, however, and the flat paint jobs seen on cars in car shows are actually specialized finish paints, not simply primers.
Stores that mix paint may offer consumers the choice between several paint finishes, from flat to glossy. People who aren't sure about which one to choose can ask for recommendations, explaining where the paint will be used and what the desired finished look and feel should be like. Staff at a paint store can recommend finishes along with colors.