punctuation

http://grammar.ccc.commnet.edu/grammar/marks/marks.htm

Full stops (periods)
A full stop is used to mark the end of a sentence that is not a direct question or an exclamation. In English the full stop is used in the same way as in Italian, but it is used more frequently. Variation in sentence length and structure contributes to creating textual meaning and orientation.

Semicolons
It is a mark of pause and linkage used to separate sentences grammatically independent but where the meaning is closely connected. Its function is to link coordiante clauses which are logically or grammatically related. It therefore stands for the conjunction and.

I arrived; I saw; I left.

In Italian, however, semicolons are not usually used to separate items in a list.

It is also used to coordiante clauses joined by a connector like however:

I had hoped there was room for me; however there wasn't.

The semicolon is used more frequently in Italian than in English, especially to identify a series of events which are not considered indipendent enough to be separeted by full stops.

Colons
With respect to semicolon, colon is not used for coordiantion. In English its function is to introduce a list of items, an explanation, an enunciation. It stands for connections like: that is, for examples, in other words, in short, etc.In English, colons are often used to introduce quotations and should be used to separate a main heading from a sub-division (e.g. Punctuation: colon). A colon is also used to introduce direct speech; in this case, the word that follows might be preceded by inverted commas.

Ex:

The sentence was poorly constructed: it lacked both unity and coherence.
My daughter finds all school subjects easy: English, History, Geography...
My name was not among the winners: I was not surprise.

English prefers a comma if the comment at the end of a sentence is not a clause but only a phrase; Italian can also have colons:

Si tratta però di una lingua grezza: come il cinese.
It is a rudimentary language, like Chinese.

Commas
Used to separate items in sentences and to groups words, phrases, clauses for clarity. Italian usage is very similar to British usage.
In English commas should be used for a purpose: to help the reader to understand the meaning, if a comma does not make the sense clearer, it is better to leave it out.

Ex.:

I am studying Italian literature and art ( Italian art, probably)
I am studying Italian literature, and art (art in general, not just Italian art) >> I am studying art and Italian literature
Would you like a glass of orange or a coke with ice in it? (the ice will be given with either)
Would you like a glass of orange, or a coke with ice in it? (the ice will be given only with the coke) >> Would you like a coke with ice in it or orange?

Use commas to separate three or more words, phrases, or clauses written in a series.

The Constitution establishes the legislative, executive, and judicial branches of government.
The candidate promised to lower taxes, protect the environment, reduce crime, and end unemployment.
The prosecutor argued that the defendant, who was at the scene of the crime, who had a strong revenge motive, and who had access to the murder weapon, was guilty of homicide.