Interstitial Lung Disease in 2020

Interstitial lung diseases (ILDs) are heterogenous and complex chronic lung diseases that even today are challenging to diagnose and classify. The terminology and mechanistic understanding of specific ILDs have evolved substantially over the last centuries and decades, and clinicians, pathologists, radiologists, and researchers are continuously working to untangle the various ILDs of differing causes. Despite many drawbacks and negative clinical trials, the unremitting work of ILD researchers have resulted in great therapeutic successes over the last decade. In this chapter, the authors present historical aspects of ILD and build a foundation to understand current and emerging concepts in ILD.