India Pale Ales hale from the famous brewing town of Burton Upon Trent and were so successful in the 19th century that they were exported all over the globe. There are many variations of IPA but they are all hoppy with quite high levels bitterness. CAMRA defines IPAs as having a minimum of 5.5% ABV so these are quite powerful beers. Many products on the market are called or advertised as IPAs but fail a long way short of this strength. It could be said that of all the beer names IPA is one of the greatest misused.
CAMRA often uses the term New World IPA to describe beers which are hop forward with the malt very much in the background, when compared to other styles of IPA such as British IPAs. New World IPAs can be sub-divided into East Coast and West Coast IPAs though there are multiple hybrid varieties. East Coast or New England IPAs (NEIPAs) have a greater malt balance then their more hop centric West Coast cousins. Several brewers are adding a touch of Lactose to their NEIPAs to produce a 'Milkshake IPA', further addition of fruit to this would send the beer into the Fruit Beer category. The use of East Coast and West Coast tends to be a flavour descriptor rather than a geographical identifier.
Note that all New World IPAs have a balance of hops, fruit and light malt and are more complex than Premium Pale Ales and Blonds with more hops, but can have fruit levels akin to New World Golden Ales and noticeably fruitier.
Colour
Straw to Pale Brown
Clarity
Cloudy through to decidedly murky, though cleater examples do exist
Carbonation
Low for cask, but bottles and cans are heavily carbonated
Alcohol
Detectable
Hop
Heavily reliant on American varieties to deliver tropical and citrus fruit, New Zealand hops can be used to give white wine notes.
Malt
Adds a degree of balance to the hops
Esters
A veritable fruit salad expect tropical fruit (mango, papaya and passion fruit) and also citrus (grapefruit, lime and lemon jelly) - but not all at the same time.
Phenols
None
Fermentation By-Products
None
Body
Full bodied, some may use the term thick
Carbonation
Low but can be higher in bottled and canned examples
Finish Length
Long and clean, particularly if couple with citrus flavours
Attenuation
More gentle and less assertive than other IPAs
Hops
Heavily reliant on American varieties such as Citra, Idaho 7, Mosaic, Galaxy, and Simcoe.
Malt
Present but still only supporting the hops
Water
No specific requirements
Yeast
Ale