Eta Carinae provides a unique example to investigate a massive star in a late evolutionary phase and how CNO-processed material is ejected and mixed with the interstellar medium. The absorbing gas surrounding Eta Carinae (η Car) shows similar characteristics to the intervening gas in spectra of gamma ray burst progenitors. Consequently, the η Car spectrum may provide clues about the nature of other extreme objects such as hypernovae and supernova impostors. In the 1840s, η Car underwent a massive ejection, which was repeated to a lesser extent in the 1890s. Today we see the Homunculus, a bipolar expanding neutral shell, and the Little Homunculus, an interior, spectroscopically time-variable, ionized structure. The η Car system is ideal as a laboratory for absorption and emission line spectroscopy. In the line-of-sight towards η Car, multiple narrow absorption lines are observed from environments with densities around 107 cm- 3 and temperatures ranging from 60 to 7000 K. Thousands of neutral/singly ionized metal lines are identified, in addition to molecular lines in species such as H2, CH, OH and NH. The input from the laboratory spectroscopy community has furthered the analysis of η Car. Future observations of η Car in the infrared through radio wavelength region will enable new detections of atomic and molecular transitions, most notably of hydrides and nitrides. We will demonstrate how experimentally derived atomic data have improved our spectral analysis, and illuminate where future work is needed.