The purpose of this paper is to introduce the basic concepts of code division multiple access (cdma) to those who are not familiar with the subject area. It briefly covers the two most important forms of spread spectrum modulation, frequency hopping (fh) and direct sequence (ds), before concentrating on cdma based on ds. The jamming margin equation is developed to give an estimate of spectral efficiency in a single-cell environment. Then the improvements in spectral efficiency based on coding and voice activation are discussed. The main advantages of cdma over more conventional access techniques in the cellular environment are discussed. Finally, the main limiting factors on cdma capacity, i.e. hand-off and power control are discussed.