Could someone explain what a "module" is in regard to British university curriculum?

Juan,
I took my degree at a British university some years ago. There were a number of compulsory subjects we had to study and then there were electives that we could choose.
Although none of these were referred to at that time as "modules", I'm thinking that the modules were the set of courses you needed to graduate. So that would be the equivelent of credits in North America.
I'm sure someone who is currently studying in the UK could shed more light on this.

When you study for a module-based degree in Britain, you cover a number of topics within your chosen field. A three-year university course will be divided into three separate academic years (or twice that amount of academic semesters). In each of these periods of study, you have to pass an examination/submit a dissertation/ write essays (or whatever) in each of a number of core modules (i.e. compulsory modules) and a number of electives (i.e. ones you can choose). Teaching is by lectures, seminars and tutorials - the latter often being one-to-one with the tutor.
The core-module approach lets the university ensure that the chosen degree subject is covered in detail, including the core modules that relate to the areas deemed essential. Then, at the end of the third year, the combined marks determine what level of degree you are awarded.
As an example, if you are studying English literature, there will be a core module on Shakespeare and Jane Austen, thus forcing you to gain some knowledge about two of our greatest writers. Then you will have to choose several elecive modules - Beckett, Lawrence or the Brontës, say, but also things like "20th Century poetry" or "the metaphysical poets" or "Dickens and Darwinism". This gives the student some leeway in determining the structure of his or her degree course but doesn't let him or her miss out the basic "must-haves". This link takes you to Keele University's English module pages. If you search for another university you'll be able to read their university handbook on-line. Alternatively, write (or telephone) the admissions officer and ask for a definition of a "module". It'll be a lt better than mine.
http://www.keele.ac.uk/depts/en/ugrad/index.htm

Thank you both. I had to convert a student's British courses to American for her major status here. You were very helpful.