Holy Priest
Rotation
Opener: Fortitude, Spirit and Shadow Protection out, Renew the tank, start Greater Heal before the first swing.
Priority: Greater Heal (downranked to fit the damage) on the tank, Flash Heal for spikes, Renew on anyone taking light damage, Prayer of Healing when three or more in a group are hurt.
Cooldowns: Spirit of Redemption is your death insurance; Holy Nova on packs in dungeons; Fade when the tank loses threat.
Forever notes: Holy stays the raid tank healer in Forever. Spirit regen between casts matters: stop casting for five seconds when you can.
Stats
Healing power, Spirit (Spiritual Guidance turns it into healing), Intellect, Spell Crit (Inspiration), then mp5.
Spirit is a real throughput stat for Holy here, not just regen.
Numbers for every spec and a gear comparer: stat weights.
Where it ranks
See the tier lists for PvE and PvP placement, and Classic vs Forever changes for what Blizzard altered in this class.
Wowhead and Icy Veins keep spec guides of their own: Icy Veins Holy Priest, Wowhead class guides. Our rotation notes are editorial, written for the Nov 2 tuning.