Dashes and hyphens are easy to get mixed up. Dashes are longer than hyphens and have different uses. Hyphens are mostly used to connect two words that come before and describe a noun.
Not: She worked for a non–profit organization
But: She worked for a non-profit organization
We use dashes instead of commas and parentheses when we want to provide more emphasis.
When the committee discovered the errors – all nine of them – they asked for a new draft.
We use en dashes, not em dashes. En dashes are shorter than em dashes and have a space either side of them.
When you’re writing about a span or range of numbers, dates or time, use “to” rather than a dash.
Not: Read pages 11–17 in the report, from 10 a.m. - 2 p.m.
But: Read pages 11 to 17 in the report, from 10 a.m. to 2 p.m.