port authority...

root port - every switch in the diameter has a root port; the port with the least cost path to the root switch

designated port - every switch in the diameter has at least one designated port; it is a port on a LAN segment (non-root port) with the least cost path to the root switch

blocking port - a port which is neither root port nor designated port

alternate port - candidate root ports although currently blocking but close to the root switch and identified by uplinkfast as suitable

forwarding port - just that, forwarding; no other stp activity expected