1) Offset refers to the horizontal distance between a seismic source and receiver. It causes a delay in the arrival time of reflections that can be corrected before stacking seismic traces. 2) Acoustic impedance is the product of density and seismic velocity, which varies between rock layers and affects the reflection coefficient at layer boundaries. 3) A seismogram contains traces recorded from a single shot point, and multiple seismograms make up a seismic section.