Porters of the late 1700's were quite strong compared to today's standards, easily surpassing 7% alcohol by volume. Some brewers made a stronger, more robust version, to be shipped across the North Sea, dubbed a Baltic Porter. In general, the style's dark brown color covered up cloudiness and the smoky/roasted brown malts and bitter tastes masked brewing imperfections. The addition of stale ale also lent a pleasant acidic flavor to the style, which made it quite popular. These issues were quite important given that most breweries were getting away from pub brewing and opening up breweries that could ship beer across the world.
View other beer types:   Altbier American Adjunct Lager American Amber Ale American Blond Ale American Imperial Stout American IPA American Pale Ale American Pale Lager American Pale Wheat Ale American Porter American Strong Ale Baltic Porter Belgian Dark Ale Belgian Double Belgian Pale Ale Belgian Quadruple Belgian Strong Dark Ale Belgian Strong Pale Ale Belgian Triple Berliner Weissbier Biere de Garde Black IPA / Cascadian Dark Ale Bock California Common / Steam Beer Cream Ale Dopplebock Dortmunder-Export Lager Double / Imperial IPA Dunkel English Ale English Barleywine English Bitter English Brown Ale English Dark Mild Ale English Porter English Stout Euro Dark Lager Euro Pale Lager European Strong Ale Flanders Red Ale Flavored / Pastry Stout Foreign-Export Stout Fruit-Vegetable Beer Gose Grodziskie Hazy / New England IPA Hefeweizen Herbed-Spiced Beer Imperial Brown Ale Imperial Pastry / Flavored Stout India Pale Lager Irish Dry Stout Irish Red Ale Kellerbier Kentucky Common Kolsch Kristallweizen Lambic Light Lager Marzen Milk / Sweet Stout Munich Dunkel Lager Munich Helles Lager Oatmeal Stout Old Ale Pilsner Rauchbier Russian Imperial Stout Saison / Farmhouse Ale Schwarze Scotch Ale / Wee Heavy Scottish Ale Session IPA Vienna Lager Weizenbock Wheat Wild / Sour Ale Winter Warmer