A semi colon has three main uses:
- To connect two clauses when they are closely related.
- e.g. The skate park was awesome; the ramps were top quality.
- To connect two clauses when the subject is the same.
- e.g. I enjoy listening to Green Day; I also enjoy listening to Red Hot Chilli Peppers.
- To separate items in a (complex) list.
- e.g. When I went shopping I bought: a black long-sleeved t-shirt with red stripes; a lava lamp that’s shaped like a rocket; and a new skateboard to replace the one I broke yesterday at the skate park.