English Breakfast is a style of black tea that is defined not by
its ingredients, but rather, by its characteristics. Its actual
composition varies, and in general, it tends to be a blend of teas
from different regions, although it rarely can be a single-origin
tea. English Breakfast tea is what the English call just "tea".
Normally, English Breakfast tea is a blend made exclusively from
black teas.
The most common types of tea used in English Breakfast blends
include Ceylon tea (from Sri Lanka), Assam (from India), and teas
from Kenya, with perhaps some Keemun (from China), although many
other types of teas can be blended in too.
The pure teas that resemble modern English Breakfast the most
are usually Ceylon teas, although Keemun more closely resembles
some of the older styles of English Breakfast tea.