Beer has throughout its history been a regionally distinct product. Styles evolved based on the ingredients, tastes and conditions of the area. Economic and geopolitical factors, as well as changing tastes and trends, have had a massive influence on regional beer styles.
Subsequently, many styles have fallen out of favour to the point of near or complete extinction. With the explosion of craft brewing came a resurgent interest in historical and forgotten beer styles, many of which have been revived from near oblivion to become very popular modern styles (witbier, Berliner weisse and gose to name a few).