To speed up things, switch will use auto negotiation to put ports in perspective roles. auto negotiation determines speed and duplex mode of every port in switch. Note that a link must be up and comes up first before STP can run on it.
Half duplex --think about old hubs, not too many of those use today's networks. Anyway, RSTP calls Half duplex ports "Shared" ports cause it cannot be sure how many devices can be connected to such port.
Point-to-point means there is only one other neighbor. having that means no chances for loops. it means Rapid switch can safety negotiate root bridge and port roles.
so u can have a switch, server, printer, or a pc on p2p port.
P2P port becomes the Edge port when u have portfast command. once BPDU is received on the Edge port, it will lose its edge status and becomes regular port .
Note; u must have portfast command (global or interface) for port to become Edge (P2p Edge). Otherwise, PC connected to p2p shows as P2p.