When should I use a 301 redirect, a 302 redirect or a canonical tag?  Don’t they do the exact same thing?

If you work even remotely close to SEO, you’ve heard these questions in one form or the other multiple times.

The short-answers:

1. Are 301s, 302s and canonicals the same thing? No.
2. When should I use 301 redirects? Whenever you’re permanently moving content to a new domain or URL, have multiple paths to the same page or when merging two sites together.
3. When should I use 302 redirects? Rarely.  Commonly used whenever an unexpected or limited time event requires redirecting traffic from a URL to a new URL temporarily.
4. When should I use Canonical tags? When you have duplicate pages and want to tell a search bot what page you’d prefer they display in results.

The long-answer:

While I could spend time reinventing the wheel, Moz put together a fantastic whiteboard post titled “Aren’t 301s, 302s, and Canonicals All Basically the Same?” that covers the long-form answers to this question.