Dashes are especially common in informal writing. They can be used in the same way as colons, semi-colons or brackets.
- There are three things I can never remember — names, faces, and I’ve forgotten the other.
- We had a great time in Greece — the kids really loved it.
Dashes, like commas, are used to add extra comments to the middle or end of a sentence.
- My mother — who rarely gets angry — really lost her temper.
- We’ll be arriving on Monday morning — at least, I think so.
A dash can introduce an afterthought, or something unexpected and surprising.
- And then we met Bob — with Lisa, believe it or not!