Terracotta ("baked earth" in Italian) is unglazed, reddish earthenware, the most familiar everyday form the material takes: garden pots, roof tiles, bricks, sculpture, and architectural ornament that are left bare rather than glazed.
Terracotta's warm red-orange color comes from the same naturally occurring iron content that gives earthenware in general its typical fired colors; left unglazed, that color is the whole visible surface, rather than covered by a glaze layer the way most functional earthenware intended to hold liquid is. Because it stays unglazed, terracotta remains fully porous, which is fine for garden pots and architectural use (a terracotta pot's porosity even helps it "breathe," evaporating some water through the pot wall itself) but means it is not watertight and is more vulnerable to frost damage than a glazed or fully vitrified body.
Terracotta's combination of workability, low firing cost, and distinctive color has made it one of the most widespread building and sculptural materials across history, used for everything from ancient roof tiles and architectural relief work to garden pots and planters still made essentially the same way today. Unglazed terracotta sculpture and architectural ornament remain common precisely because the material's own color and texture are the finished surface, not a base to be covered.
Large sculptural and architectural terracotta work needs particular care to survive its own firing: a solid mass of clay thick enough for a large form is prone to cracking as it dries and fires unevenly through its full thickness, so sculptural terracotta bodies are typically heavily grogged, which opens the body enough for trapped gases and moisture to escape evenly, and large pieces are often built or carved hollow rather than solid, a construction method common in architectural terracotta from the 19th century onward.
Terracotta is among the oldest and most geographically widespread materials in human material culture, used across essentially every ancient civilization that worked clay: Mesopotamian cuneiform tablets, cylinder seals, and figurines from as early as 6000 BCE; Greek and Roman architectural terracotta, roof tiles, and figurines; and China's terracotta army figures from the Qin dynasty are among the best-known examples of the material used at monumental scale. Its low cost and ready availability relative to carved stone made it a practical choice for both everyday objects (storage jars, cooking vessels, bricks, roof tiles) and sculpture across cultures with otherwise very different artistic traditions, and its durability once fired means terracotta objects often survive from periods where more perishable materials have not.
Because it stays unglazed and porous, terracotta left outdoors in a freeze-thaw climate is prone to cracking as absorbed water expands on freezing, which is why terracotta garden pots are a recurring casualty of winter weather in colder regions. Functional terracotta meant to hold liquid, rather than serve as a planter or ornament, needs a glaze on at least its interior surface the way any other earthenware would.