Special letters are:

ą	"Nasal o" Somewhat similar to French or Portuguese on and a little bit like English own. Before b or p, it is closer to om: Dąbrowski > "Dombrovski" You may notice: before ł, it is generally pronounced colloquially as o.
ć	Soft tch. Similar to but clearly softer than cz.
ę	"Nasal e". Pronounced rather like en. Before b or p, it is closer to em. You may notice: 1) when it's the last letter in a word, or 2) before l or ł it is generally pronounced colloquially like a regular Polish e, slightly lengthened.
Ł ł	L with stroke was originally a special type of l. In modern Polish it's pronounced like an English w like in will. The older pronunciation is still acceptable and understood by most Poles.
ń	Pronounced like soft n in onion. Similar to Spanish ñ and French gn.
ó	Exactly the same as u, like tool or soup.
ś	Soft sh. Similar to but clearly softer than sz.
ź	Soft zh. Similar to but clearly softer than ż and rz.
ż	Hard zh. Sounds exactly the same as rz. Fairly similar to Zhivago and French je suis.

Special letter combos are:

au	loud. Exception: Compound words formed by a word ending in a and another starting with u, for example, words beginning with a prefix na or za such as nauczyć and zaufać. In that case, the vowels a and u are pronounced separately.
ch	Same as h.
ci	c followed by i is pronounced as a very soft tch just like ć. Note that if ci is followed directly by another vowel, the i serves only to produce the soft tch sound. Thus, ciastko (cookie) could be misspelled "ćastko".
cz	Hard tch. Fairly similar to chip.
dz	cads
dź	Somewhat similar to gene. Similar to but softer than dż.
dzi	dz followed by i is pronounced just like dź. Note that if dzi is followed directly by another vowel, the i serves only to produce the dź sound, hence, dziadek (grandfather) could be misspelled "dźadek".
dż	John.
eu	Similar to eł
rz	Hard zh. Sounds exactly the same as ż. Fairly similar to Zhivago or French je suis. May be pronounced sh after k, p, or t.
si	s followed by i is pronounced as a very soft sh just like ś. Note that if si is followed directly by another vowel, the i serves only to produce the soft sh sound. Thus, siatka (net) could be misspelled "śatka".
sz	Hard sh. Fairly similar to ship.
zi	z followed by i is pronounced as a very soft zh just like ź. Note that if zi is followed directly by another vowel, the i serves only to produce the soft zh sound. Thus, ziarno (grain) could be misspelled "źarno".

Dialects

The Polish language became far more homogeneous in the second half of the 20^th century, in part due to the mass migration of several million Polish citizens from the eastern to the western part of the country after the east was annexed by the Soviet Union in 1939, during World War II.

"Standard" Polish is still spoken somewhat differently in different regions of the country, although the differences between these broad "dialects" are slight. The differences are slight compared to different dialects of English, for example.

Some more characteristic but less widespread regional dialects include:

1.        The distinctive Góralski (highlander) dialect is spoken in the mountainous areas bordering the Czech and Slovak Republics. The Górale (highlanders) take great pride in their culture and the dialect. Most urban Poles find it difficult to understand this very distinct dialect.

2.        In the western and northern regions that were largely resettled by Poles from the territories annexed by the Soviet Union, the older generation speaks a dialect of Polish characteristic of the Eastern Borderlands.

3.        The Kashubian language, spoken in the Pomorze region west of Gdańsk on the Baltic sea, is closely related to Polish, and was once considered a dialect by some. However, the differences are significant enough to merit its classification as a separate language; for instance, it is not readily understandable to Polish speakers unless written. There are about 53,000 speakers according to the 2002 census.

4.        Poles living in Lithuania (particularly in the Vilnius region), Belarus (particularly the northwest), and in the northeast of Poland continue to speak the Eastern Borderlands dialect which is more "slushed", and is easily distinguishable.

5.        Some city dwellers, especially the less affluent population, had their own distinctive dialects. An example of this is the Warsaw dialect, still spoken by some of the population of Praga district, on the eastern bank of the Vistula.

6.        Many Poles living in emigrant communities, e.g. in the USA, whose families left Poland just after World War II, retain a number of minor features of Polish vocabulary as it was spoken in the first half of the 20^th century, but which now sound archaic to contemporary visitors from Poland.