Basic

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 a special rule 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).

From the Comprehensive Rules (June 7, 2024—Modern Horizons 3)

• 205.4c Any land with the supertype “basic” is a basic land. Any land that doesn’t have this supertype is a nonbasic land, even if it has a basic land type.
  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 and have received errata in the Oracle card reference accordingly: Forest, Island, Mountain, Plains, Swamp, Snow-Covered Forest, Snow-Covered Island, Snow-Covered Mountain, Snow-Covered Plains, and Snow-Covered Swamp.

From the Comprehensive Rules (June 7, 2024—Modern Horizons 3)

• 305.5. 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. See rule 205.3i for the complete list of land types.

  Example: “Basic Land — Mountain” means the card is a land with the subtype Mountain.

From the Comprehensive Rules (June 7, 2024—Modern Horizons 3)

• 305.6. 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. An object with the land card type and a basic land type has the intrinsic ability “{T}: Add [mana symbol],” even if the text box doesn’t actually contain that text or the object has no text box. For Plains, [mana symbol] is {W}; for Islands, {U}; for Swamps, {B}; for Mountains, {R}; and for Forests, {G}. See rule 107.4a. See also rule 605, “Mana Abilities.”

From the Comprehensive Rules (June 7, 2024—Modern Horizons 3)

• 305.8. Any land with the supertype “basic” is a basic land. Any land that doesn’t have this supertype is a nonbasic land, even if it has a basic land type.

Nonbasic

• Nonbasic refers to every land without the Basic supertype, or "special lands".

Trivia

• Although Relentless Rats and Shadowborn Apostle are not bound by the four-card maximum, they do not have the supertype basic.