The semicolon is used less frequently than the full stop and comma. Some writers avoid it altogether because they are unsure about how to use it. However, it is worth learning how to use the semicolon effectively to link grammatically distinct but closely related ideas. For example:

The siege came to an end; the invaders left the city and the local population emerged from hiding.

It would of course be possible to use a full stop instead of a semicolon in this example, but the semicolon highlights the strong relationship between the two ideas.

For the same reason, the semicolon is often used instead of a full stop before connectors such as ‘therefore’, ‘thus’, ‘however’, ‘nevertheless’, ‘in other words’, ‘conversely’.

There has been a significant increase in the price of food; therefore, it is likely that inflation will rise in the next quarter.

There has been a great deal of research into bilingualism; however, little is known about the acquisition of a third or fourth language.

The semicolon can also be used to separate complex items in a list, particularly if the items contain commas. Used in this way, the semicolon helps to avoid confusion:

The robot has four wheels with brakes; a wireless video camera; four ultrasonic sensors and four contact sensors that allow it to roam without bumping into objects; and a sound card and speakers that enable it to give oral feedback to users.