Narrow-Line Seyfert 1s: 15 Years Later

The spectroscopic properties of the objects that came to be called Narrow-Line Seyfert 1s were first systematically described and named as such 15 years ago by Osterbrock & Pogge (1985). At the time, they were a relatively rare and peculiar subclass of Seyfert galaxies. Their discovery in large numbers in X-ray surveys, however, has elevated them to a role as important members of the AGN family, ones which may hold many keys to understanding the physics of AGN across the electromagnetic spectrum. This contribution reviews the spectral classification of the narrow-line Seyfert 1s, and describes some of the properties that make this unusual class of objects interesting.