An average-strength to moderately-strong British bitter ale. The balance may be fairly even between malt and hops to somewhat bitter. Drinkability is a critical component of the style. A rather broad style that allows for considerable interpretation by the brewer.
In England today, "ESB" is a Fullers trademark, and no one thinks of it as a generic class of beer. It is a unique (but very well-known) beer that has a very strong, complex malt profile not found in other examples, often leading judges to overly penalize traditional English strong bitters. In America, ESB has been co-opted to describe a malty, bitter, reddish, standard-strength (for the US) British-type ale, and is a popular craft beer style. This may cause some judges to think of US brewpub ESBs as representative of this style.
Bass Ale, Highland Orkney Blast, Samuel Smith's Old Brewery Pale Ale, Shepherd Neame Bishop's Finger, Shepherd Neame Spitfire, West Berkshire Dr. Hexter's Healer, Whitbread Pale Ale, Young's Ram Rod