These are one of the most misused features of English punctiation. They are mainly used in two situations: 

(a) to show contractions 

        He's the leading authority 

(NB. contractions are not common in academic English) (take notice)

(b) with possessive

      The professor's secretary (singular)

      Student's marks (plural) 

These are used to show the link between two connected phrases, when a comma would be too weak and a full stop too strong.  

        20 people were interviewed for the first study; 33 for the second.

Semi- colons are also used to divide up items in a list when they have a complex structure, as in a multiple citation: 

      (Maitland, 2006; Rosenor, 1997; New scientist, 2006b; University of Michigan, 2000)

(a) to introduce explanations

       The meeting was postponed: the Dean was ill. 

(b) to start a list

     Three aspects were identified: financial, social and ...

(c) to introduce a quotation

There is some flexibilty in the use of commas, and overuse can slow down the reader.

(a) Single quotation marks are used to emphasise a word:

The word 'factory' was first used in the seventeenth century.

to give quotations from other writers:

Goodwin's (1977) analysis of habit indicates that, in general, 'it will be more difficult to reverse a trend than to accentuate it'.

to show direct speech:

'Can anyone find the answer?' asked the lecturer.

NB. Longer quotations are usually indented (i.e. have a wider margin) and/ or are set in smaller type.

(American English uses double quotation marks to show quotations).

(b) Double quotation marks are used to show quotations inside quotations (nested quotations):

As Kauffman remarked: 'his concept of "internal space" requires close analysis.'

(c) In references, quotation marks are used for the names of articles and chapters, but book or journal titles normally use italics:

Russell, T. (1995) 'A future for coffee?' Journal of Applied Marketing 6, 14-17.     

Hyphens (- ) are used with certain words and structures:

well-engineered/ co-operative/ three-year-old

Exclamation marks (!) and question marks (?)

'Well!' he shouted, 'Who would believe it?'

Brackets or parentheses () can be used to give additional detail:

Relatively few people (10-15 per cent) were literate in sixteenth-century Russia.     

(a) The study was carried out by Christine Zhen-Wei Qiang of the National University of Singapore.

(b) Professor Rowan's new book, The End of Privacy, is published in New York.

(c) As Keynes said: 'It's better to be roughly right than precisely wrong'.

(d) Three departments—Law, Business, and Economics—have had their funding cut.

(e) As Cammack (1994) points out, Latin America is creating a new phenomenon: democracy without citizens.

(f) Thousands of new words, such as 'app', enter the English language each year.

(g) The BBC's World Service is broadcast in 33 languages, including Somali and Vietnamese.

(h) She scored 56 percent on the main course. The previous semester, she had achieved 67 percent.

The School of Biomedical Sciences at Borchester University is offering two undergraduate degree courses in neuroscience this year. Students can study either Neuroscience with Pharmacology or Neuroscience with Biochemistry. There is also a master's course, which runs for four years and involves a period of study abroad during November and December. Professor Andreas Fischer is the course leader for neuroscience, and enquiries should be sent to him via the website.