Conceptual density functional theory (DFT), also called Density Functional Reactivity Theory or Chemical DFT, is the chemical reactivity theory of DFT. Its framework and some recent developments of Conceptual DFT are briefly reviewed in this article. Introduced in more detail are the reactivity indices such as electronegativity, hardness, softness, Fukui function, electrophilicity index, as well as principles derived from them. Two representative recent developments, the dual descriptor and steric effect quantification, are succinctly summarized. A personal prospective on the future of Conceptual DFT is provided at the end.