Basic

From MTG Salvation Wiki

Basic is a supertype found on the basic lands Plains, Island, Swamp, Mountain, Forest, Snow-Covered Plains, Snow-Covered Island, Snow-Covered Swamp, Snow-Covered Mountain, Snow-Covered Forest.

A card with the Basic supertype has special rules associated with it: it is not bound by the four card maximum rule that other cards are restricted to in constructed decks.

The word basic was first seen on the basic lands in Eighth Edition in order to help players understand what exactly the term meant, as the basic land types (Plains, Island, Swamp, Mountain and Forest) were not always associated with basic lands (such as the original dual lands printed in the Beta set).

Although Relentless Rats is not bound by the four-card maximum, it does not have the supertype basic.

From the Comprehensive Rules

205.4b Any land with the supertype “basic” is a basic land. Any land that doesn’t have this supertype is a nonbasic land.
- Example:
  Note that cards printed in sets prior to the Eighth Edition core set didn’t use the word “basic” to indicate a basic land. Cards from those sets with the following names are basic lands: Forest, Island, Mountain, Plains, Swamp, Snow-Covered Forest, Snow-Covered Island, Snow-Covered Mountain, Snow-Covered Plains, and Snow-Covered Swamp.
212.6f Land subtypes are always a single word and are listed after a long dash. Land subtypes are also called land types. Lands may have multiple subtypes.
- Example:
  “Basic Land — Mountain” means the card is a land with the Mountain subtype.
212.6g The basic land types are Plains, Island, Swamp, Mountain, and Forest. If an object uses the words “basic land type,” it’s referring to one of these subtypes. A land with a basic land type has an intrinsic ability to produce colored mana. (See rule 406, “Mana Abilities.”) The land is treated as if its text box included, “: Add [mana symbol] to your mana pool,” even if the text box doesn’t actually contain text or the card has no text box. Plains produce white mana; Islands, blue; Swamps, black; Mountains, red; and Forests, green.

Card types
Groups	Supertypes	Card types	Subtypes
Spell (non-permanent)		Instant	Trap	Arcane
Spell (non-permanent)		Sorcery		Arcane
Permanent	Basic, Legendary, Snow, World	Artifact	Equipment, Fortification, Contraption
		Creature	(...)
		Enchantment	Aura, Shrine
		Land	(...)
		Planeswalker	(...)
Miscellaneous		Tribal	(...)
		Plane	(...)
		Vanguard
Obsolete	Mono, Poly, Continuous	Interrupt, Mana Source