What are the rules for the US Supreme Court to decide to hear a case?

I thought it only took two justices to agree that a case should be heard at the US Supreme Court (noo idea where I got that notion). The article below suggests to me it needs something more. So, what is the procedure at the US Supreme Court for them to decide to hear a case?

(remember this is GQ)

It’s four justices, by practice.

Rule of four - Wikipedia