The term beer generically includes a wide berth of beverages -virtually every style of fermented malt beverage. Beer is inclusive of all ales and lagers and the many unique styles that fall under those headings.
Ales date back to antiquity; lager beers are only several hundred years old.
Ales are top-fermented at relatively warm temperatures for short periods of time. Top fermentation means that the yeasts float on top of the beer during fermentation. Style categories include Pale Ales and Brown Ales.
Lagers use the (months) longer cold fermented process with yeasts that sink to the bottom of the barrel during fermentation. Style categories include and Pilsners and Dark Lagers.
When brewers decide to mix it up and cross the fermentation methods and yeast varieties typically used in ale and lager brewing is classified as a new third category of beer called a hybrid or specialty beer.
Typically, these beers are brewed in a classic style recipe e.g.: Porter or Weizenbier, with newly added flavors. Obviously, this is an exciting and limitless category where imagination is key.