Historical Rules · 1 October 2012
Rule 110.4
Official source text from the 1 October 2012 Rules release
There are five permanent types: artifact, creature, enchantment, land, and planeswalker. Instant and sorcery cards can't enter the battlefield and thus can't be permanents. Some tribal cards can enter the battlefield and some can't, depending on their other card types. See section 3, "Card Types."