The term pale ale originally denoted an
ale that had been brewed from pale malt. The pale ales of the
early 18th century were lightly hopped and quite different from
today's pale ales. By the mid-18th century, pale ale was mostly
brewed with coke-fired malt, which produced less smoking and
roasting of barley in the malting process, and hence produced a
paler beer. One such variety of beer was October beer, a pale,
well-hopped brew popular among the landed classes, who brewed it
domestically; once brewed it was intended to cellar for two
years.
IPA stands for India
Pale Ale, a hoppy style of beer within the pale ale category.
Double IPAs are a much hoppier style of IPAs with alcohol
content above 7.5 percent by volume. The India pale ale name is
a result of its popularity with British troops stationed in
India in the 19th century, when the subcontinent was still a
British colony.