Models for radiation transport in simple geometries are developed, with an emphasis on self-shielding and distributed sources. Three mechanisms for gamma ray attenuation—photoelectric, Compton, and pair production, are described. Some end-to-end calculations are shown for the estimated count rates with realistic sources and detectors. The impact of background radiation in potentially masking a source from detection is explored. Radiation background sources in the ground and air are described, with particular emphasis on the uranium and thorium decay chains, with tables of the characteristic gamma-ray lines given. Cosmogenic radiation is also explored, along with neutron backgrounds. Next, the impact of naturally occuring radioactive material (NORM) and technologically enhanced NORM (TENORM) are discussed.