Mental retardation is a condition mainly found in children, which is quantified by two factors:

Mild mental retardation is indicated by an IQ of 52-68, moderate retardation by an IQ of 36-51, severe retardation by an IQ of 20-35 and profound retardation by an IQ of 19 or below.

The mildly retarded are able to learn how to speak, interact socially, walk, write and can be educated up to a sixth grade level by their late teens. They are usually able to work and conform to societal standards, but may need assistance in times of stress.

The moderately retardated are able to talk or communicate, but are relatively socially unaware. Education beyond the equivalent of the second grade is unlikely, and they may be able to do unskilled work.

The severely retarded can only learn a very small number of words, have very few, or no modes of expression and have very poor muscle coordination. They are able to learn a very limited set of self-help skills in a controlled environment.

The profoundly retarded have very poor muscle coordination, little to no ability to care for themselves and almost always need nursing care.