At the time of the 1988 census Poland had a population of 37,878,641.
The 1998 estimate was 38,606,922, yielding an average population
density of 123 persons per sq km (320 per sq mi).
Poland's highest population densities are in the southern upland
areas; the lowest densities are in the northwest and northeast.
The average annual rate of population growth was very high in
the period following World War II, but after the 1960s it declined
to less than 1 percent, and in 1997 the population was estimated
to be decreasing.
Polish is the official language of Poland and is used by nearly
all of the population. The language contains a number of dialects,
some of which are intermediate between Polish and German or Ukrainian.
The Polish language is written using the Latin alphabet and includes
some letters that are additional to those used in the English language
(see Polish Language). Some members of ethnic groups speak their
own native languages in addition to Polish.
Roman Catholicism has played a very important role in Polish history
and serves as a cornerstone of Polish identity.