So, once again The Oatmeal has managed to put into a short, amusing cartoon what many people take years to get to grips with: the semicolon. Some people are almost 'afraid' to use the semicolon for fear that they'll use it incorrectly. The rules of usage are actually pretty simple, and can be boiled down to 3 occasions:
1. Linking together two related sentences without the use of a conjunction.
e.g. "I've never eaten pigeon; I assume it tastes a lot like chicken."
2. Linking together two sentences which already contain punctuation.
e.g. "For the life of me, I can't remember where I put my keys; I must have left them at work."
3. Separating items in a list where there are already commas used within the items themselves. (Usually used with place names)
e.g. "Replicas of the Eiffel Tower can be found in Las Vegas, Nevada, USA; Hangzhou, China; and Crailsheim, Germany."
Check out the comic for more examples of correct semicolon usage!