A self-consistent continuum (fluid) model for a radio-frequency discharge is presented. The model is one dimensional, incorporates an electron energy balance, and is valid for both electropositive and electronegative discharges. A connection of the fluid model with the underlying physics is presented: issues such as the derivation of the fluid equations from moments of the Boltzmann equation, the closure of the set of moments, and the fundamental assumptions behind the fluid equations are discussed. A detailed set of results for an electropositive and an electronegative discharge is presented, and contrasted. The sustaining mechanisms and the electrical characteristics of the two discharges are also discussed. Comparison with experimental data of spatially and temporally resolved plasma induced emission is successfully done.