The semicolon is somewhere between a full stop and a comma. Semicolons can be used in English to join phrases and sentences that are thematically linked without having to use a conjunction (example 1 below). Semicolons can also be used instead of commas to separate the items in a list when the items themselves already contain commas (example 2 below).
- I like your brother; he's a good friend.
- Many great leaders, Churchill, leader of Britain during the Second World War; Alexander, the great Emperor and general; and Napolean, the brilliant French general, had strong characters, which were useful when their countries were at war but which did not serve them well in times of peace.