Some classes must choose their spells in advance of casting them. Resting makes these spells available for casting.
Prepared casting[]
The cleric, druid, paladin, ranger, and wizard classes require spell preparation. However Clerics and Druids may also use spontaneous casting.
A character can prepare only spells they know for each class. The character uses a single spell slot for each instance of a spell they prepare.
Spontaneous casting[]
Clerics and Druids can use spontaneous casting to cast spells they haven't prepared in exchange for losing a spell they have prepared.
Unprepared casting[]
Sorcerers, bards, favored souls, and spirit shamans cast their spells without having to prepare them in advance. They may cast any of their spells known, however they generally know fewer spells than preparation spellcasters.
Warlock invocations do not need to be prepared, and unlike spontaneous casters and most spell-like abilities, have no limit to the amount cast per day.
Domain spells[]
Clerics recieve a bonus spell slot for each spell level from 1st level upwards. This slot may not only be used for the preparation of spells gained from the cleric's domains, but for any spell she knows.