Flat paint is the most common type of paint used in houses. It is extremely durable and can be easily washed with soap and water. It is the best paint to use if there are imperfections in the wall being painted as its lack of sheen hides these problems.
Eggshell paint, even more durable than flat paint, has more of a sheen to it and provides a soft luster to the room. Eggshell provides a harder finish and is not as soft as a flat paint, but does give the room a natural shine without overdoing it in terms of sheen.
Gloss paint has the highest sheen of all of the different types of paint and is one of the most widely used choices in bathrooms. While it does make imperfections more noticeable than either the flat or eggshell, it is more stain resistant and holds up better against constant moisture.
Semi-gloss paint is even more durable than eggshell paint and provides an alternative with less sheen than the gloss, but more than the flat or eggshell. Semi-gloss is also a good choice in bathrooms due to its stain resistance and ease for cleaning. It also does not hide imperfections as well as the flat paint, but provides more in terms of luster.