Chalmers Writing Guide

Punctuation

In English, punctuation, like a comma and a semi-colon, helps make the meaning of a sentence unambiguous. A coherent sentence requires appropriately used punctuation and this will depend on the kind of sentence written and the message meant. The wrong punctuation could change the meaning completely. Compare:

1. Frequently changed grades lead to dissatisfied students.

2. Frequently, changed grades lead to dissatisfied students.

In the first sentence, only the grades are frequently changed, which the students do not like, whereas in the second sentence, the fact that grades are changed often upsets the students.

The most commonly confused punctuation symbols are the comma, colon and semi-colon.  In the tables below, you will find information about these and examples of their use.  It is important to be aware of their functions in the English language as punctuation rules are not always the same in all languages.


Comma


Colon



Semi-colon



In Summary

Full-stop 
– used to end a complete sentence, longest of pauses.

Comma
– show where pauses are placed
– enclose extra information
– enclose a non-defining relative clause
– increase clarity where ambiguity is possible
– to separate items in a list, to separate adjectives in a series
– to link a dependent and an independent clause when the former starts a sentence
– numbers.

Semi-colon
– longer pauses than commas, but not as long as a full-stop
– connect two independent phrases where meaning is closely connected and no coordinating conjunction is used
– longer lists

Colon
– not used to provide pauses
– introducing a list or a subdivision of a subject