Italy is a young and an old country at the same time!
What does it mean?
Even though most of its cities, towns and villages were founded before Christ's birth, Italy was unified only in 1861 or, better to say, in 1870. Trento joined Italy in 1918 and Trieste in 1954.
So Italy is still "many countries" with different dialects, cuisines, traditions and people! The consequence is we have a great linguistic variety.
Sometimes I hear my italian students saying: I was convinced to know Italian quite well but why I wasn't able to undestand much when I went to Palermo?
It's simple: standard Italian doesn't exist or, better to say, it only exists on television, in the news, on the radio, at university or in the books.
I have to confess sometimes I have some difficulties to understand people from the North Italy with a strong accent speaking on the phone, you know, without visual interaction!
Of course we have a national language so if you speak standard Italian you can communicate as well and everyone is able to understand you all over Italy!
Anyway in the actual fact we actually speak regional Italian or dialect in our families, with friends or in popular markets.
What is regional Italian?
It's a grammatically correct Italian with a tune of voice and accent that derives from the local dialect!
So we can say that regional Italian is the language really spoken by Italians who respect grammar rules with a local pronunciation.
STANDARD ITALIAN + DIALECT = REGIONAL ITALIAN
Dialects are on the contrary autonomous local languages coming from the oral Latin. There are many types of dialects in Italy and they are used a lot.
Now you are probably wondering what you can do to learn Italian and which kind of Italian is better for you!
The answer is of course standard Italian! This is very important until you get to an upper-intermidiate level ! Then, if you'll be living in Italy for a long time it will be normal to learn some words and sentences in dialect.