In this chapter some typical records as obtained on land and at sea are analyzed. On land, typically, events such as direct waves, refracted/head waves, surface waves and reflections can directly be observed in records. From these events velocities and estimates of depths can be obtained. At sea, typically, events such as direct waves, refracted/head waves, reflections and multiple reflections can directly be observed in raw records. or both those cases on land and at sea, a first model for the subsurface is estimated (where the model is here seen as the first interpretation of the data). Using the Fourier transformation, a filtering example is shown with the aim to separate different events in these raw records.