This chapter considers some of the fundamentals associated with the basic datasets from which the asteroseismic and other intrinsic stellar parameters are extracted (usually lightcurves of photometric observations or time series of Doppler velocity observations). In particular, the chapter looks at how the observational technique affects the amplitudes of the observed oscillations. It also introduces the other intrinsic stellar signals that manifest in the data, specifically those due to granulation (signatures of near-surface convection) and magnetic activity. The chapter's aim is to familiarize the reader with the basic content of the typical data and lay some important groundwork for the detailed presentations that follow in the next two chapters.