Every casting class in EverQuest Legends learns some spells for free as it levels and has to buy or hunt down the rest. Knowing which is which is the difference between a smooth climb and wasting platinum. Look up any spell, or open a class list to plan your whole spellbook.
Handed to you automatically at the right level, at no cost. You never need to buy these, just keep leveling and they appear in your spellbook.
Bought from a spell vendor, or found as a drop, quest reward, or research. These are where your early platinum goes, so buy the ones that matter.