When should a writer use a dash?

Question

to set off an introductory word or phrase
to separate clauses in a compound sentence
to indicate an abrupt shift in idea
to separate items in a list

Answer 1

A writer should use a dash primarily to indicate an abrupt shift in idea. Dashes can also be used to set off additional information or commentary, as well as for emphasis.

The other options you mentioned typically involve punctuation marks like commas or semicolons:

• Introductory words or phrases are generally set off by commas.
• Clauses in a compound sentence are usually separated by commas or semicolons, depending on the structure.
• Items in a list are typically separated by commas.

While dashes can be used creatively in various ways, their primary role is to create emphasis or indicate breaks in thought.