Harley-Davidson Inc. (H-D or Harley), is an American motorcycle manufacturer. Founded in Milwaukee, Wisconsin, during the first decade of the 20th century, it was one of two major American motorcycle manufacturers (Indian being the other) to survive the Great Depression.

Classic Harley engines are Small V-twin and Big V-twin engines, with a 45° angle between the cylinders. This 45° angle causes the cylinders to fire at uneven intervals and produces the choppy “potato-potato” sound so strongly linked to the Harley-Davidson brand.

Modern Harley-branded motorcycles fall into one of six model families, distinguished by the frame, engine, suspension, and other characteristics.

The Touring family, also known as “dressers” or “baggers”, includes Road King, Road Glide, Street Glide and Electra Glide models. Touring models use Big-Twin engines and large-diameter telescopic forks.

The Softail family includes Night Train, Deuce, Springer, Fat Boy, Heritage, Bad Boy and Cross Bones. Softail models utilize the Big-Twin engine and the Softail chassis. With the rear-wheel suspension hidden under the transmission, they are visually similar to the “hardtail” choppers popular in the 1960s and 1970s, as well as from their own earlier history.

The Dyna family includes the Sturgis, Daytona, Super Glide, Street Bob, Low Rider, Fat Bob, Switchback and Wide Glide. Dyna models also utilize the Big-Twin engine.

The Sportster family, conceived as racing motorcycles, were popular on dirt and flat-track race courses through the 60s and 70s. Smaller and lighter than other models, contemporary Sportsters with 883 cc or 1,200 cc Evolution engines, remain similar in appearance to their racing ancestors. The Sportster family includes the Iron883, Café Racer, Superlow, Hugger, Roadster, Forty-Eight, Seventy-Two and Nightster.

The VRSC (V-Rod) family bears little resemblance to Harley’s more traditional lineup. Competing against Japanese and American muscle bikes, the V-Rod makes use of the Revolution engine developed jointly with Porsche that, for the first time in Harley history, incorporates overhead cams and liquid cooling. The V-Rod is visually distinctive, easily identified by the 60-degree V-Twin engine, the radiator and the hydroformed frame members. V-Rod models include the Night Rod, Street Rod, Muscle, Screamin’ Eagle and the drag racing Destroyer.

The Street family is Harley’s first all new platform in thirteen years, and was designed to appeal to younger riders looking for a lighter bike. The Street 750 uses an all-new, liquid-cooled, 60° V-twin engine called the Revolution X. A six speed transmission is used.

Harleys are noted for the tradition of heavy customization that gave rise to the chopper style of motorcycle and have long been associated with the sub-cultures of the biker, motorcycle clubs, and Outlaw motorcycle clubs.