Colon between title and subtitle

Question

A colon is often put between the title and the subtitle of essays and articles.

Is it necessary? Can I drop it?

Answer 1

It's convention for a reason. Without the colon, it can be hard to figure out where the main title ends and the subtitle begins.

Oliver Twist The Parish Boy's Progress

Oliver should twist what?

Oliver Twist: The Parish Boy's Progress

That is better.

Note that an semi-colon is often used when introducing an alternate title:

Peter Pan; or, the Boy Who Wouldn't Grow Up