While the term 'association areas' is well established among those engaged in neurology and its related sciences, it is difficult to say precisely what it means. This review tries to better define it, and begins with a brief discussion of its history, how it came about and finally gained wide acceptance. I introduce the work of Theodor Meynert (1833-1892), and Paul Flechsig (1847-1929), both of whom played important roles in brain mapping. Furthermore, I review how the term is linked to the work of Joseph Jules Dejerine (1849-1917) on white matter, and to disconnection syndrome as proposed by Norman Geschwind (1926-1984). Lastly, I focus on brain maps, historically essential to the study of association areas, and discuss the numbering of brain areas.