If someone uses a card draw spell, is that spell targeting the card they draw? Like does it target the top card of their library, or is it just implied?
It does not say "draw target card", so it doesn't target anything. Effects can affect things without targeting them.
The only "implied" targets in Magic are for Aura spells (they target whatever they are going to enchant), and for some keywords such as Equip (check their rules or reminder text for the word "target"). Everything else only targets if it says "target" on its text.
If someone uses a card draw spell, is that spell targeting the card they draw? Like does it target the top card of their library, or is it just implied?
I'm curious: what situation came up to make you ask this question?
To see if [[Radiate]] could get someone to mill every players library in the game.
Radiate can target any "instant or sorcery spell that targets only a single permanent or player". This includes Ancestral Vision or Psychic Spiral (which can each target only a single player), but not Nature's Spiral (which can target neither a permanent nor a player [C.R. 110.1, 102.1]), or Roiling Waters, if it targets both a creature and a player, or Divination, which has no targets at all (C.R. 115.1a, 115.9b-c).
Note that a card in a player's library is neither a permanent nor a player (C.R. 110.1, 102.1).
RULES OF MAGIC :
http://magic.wizards.com/en/game-info/gameplay/rules-and-formats/rules
The only "implied" targets in Magic are for Aura spells (they target whatever they are going to enchant), and for some keywords such as Equip (check their rules or reminder text for the word "target"). Everything else only targets if it says "target" on its text.
RULES OF MAGIC :
http://magic.wizards.com/en/game-info/gameplay/rules-and-formats/rules
Card tags fixed. See your private messages to learn how to do them here. -MadMage
Note that a card in a player's library is neither a permanent nor a player (C.R. 110.1, 102.1).