The semicolon is in between the comma and the full stop in terms of strength. Generally speaking, it is closer to a full stop than to a comma, since it can separate two sentences. It is used in the following three situations, which are described and exemplified below, namely between two related sentences, before connectors, and in lists.
Between two related sentences
We may use a semicolon to separate two sentences which are closely related in theme or content:
(1) Come to my office tomorrow; I will have the document prepared.
(2) Few newly enrolled students know exactly what career path their studies will eventually offer; most find their area of interest during their studies.
The second sentence/main clause does not start with a capital letter in such a case, unless it is a word that always starts with a capital letter.
We may use a semicolon before a connecting word.
To the category of connecting words, we may refer the following adverbs: also, anyway, besides, consequently, furthermore, hence, however, incidentally, indeed, moreover, nevertheless, next, nonetheless, otherwise, similarly, still, then, therefore, and thus.
(3) The deadline for the assignment is due tomorrow; therefore, additional study time has been scheduled.
(4) Exams are a means of measuring ability; however, not everyone performs well in them.
We may also use a semicolon before a connecting phrase.
The following phrases may have such a connecting function: after all, as a matter of fact, as a result, at the same time, even so, for example, for instance, in addition, in conclusion, in fact, in other words, in the first place, of course, on the contrary, and on the other hand.
(5) Exams are a means of measuring ability; as a result, not everyone performs well in them.
(6) Critical thinking is essential at university; at the same time, it is difficult to teach.
Semi-colons as used to separate complex items in a list in which some of the items already contain commas:
(7) There are many faculties at a university: Arts; Behavioural, Cognitive and Social Sciences; Humanities; Environmental and Rural Science; Science and Technology; Business, Economics and Public Policy; Law; Education; and Rural Medicine and Health.
Some reference systems, such as Harvard, use semicolons to separate in-text references when citing more that one item.
(8) (Jones 2007; Johansson & Olofsson 1998; Strongman et al. 2003)