Standardized tests are tests that have been prepared with questions specially aimed at the identification of achievement levels. These types of tests are created with a great deal of research that has been aimed at identifying what areas of knowledge and skills are typical at what ages and education levels.
These tests are then given to large numbers of test recipients covering the full spectrum of ages and education levels that the test is being aimed at to see if it seems to accurately measure what is attempting to measure. This process is called "standardization."
Once standardized, these types of tests are used to measure IQ and achievement in relation to age and educational levels and are used in schools, psychological practices, prisons, the military and many other venues. The SAT and Iowa Test of Basic Skills (ITBS) exams are examples of standardized tests.