The goal of this article is to discuss properties of functional categories in the framework of Chomsky (1999)`s minimalist theory. We will divide core functional categories of English into sixteen types of categories and specify their syntactic properties in terms of EPP feature, EPP tense feature, and EPP affix feature. We will justify the necessity of the EPP tense feature and the EPP affix feature on the empirical basis of English data. The notion of EPP affix feature will be justified on empirical grounds.