土 pictures a small mound of earth heaped on the ground line. The earliest oracle bone forms suggest a sacrificial earth altar — a small pile of soil set apart for ritual. Identical across 繁體 / 新字体 / 简体.

土 sits at the center of the East Asian Five Phases system (五行: wood, fire, earth, metal, water) — every other element gets a planet and a weekday in the seven-day cycle. Saturday is "earth day" (Saturn, the earth planet).

As a radical, 土 marks any character involving soil, ground, or built things made from earth: 地 (ground), 場 (place — originally a flat earthen area), 城 (city wall, built of pounded earth), 坊 (block/quarter), 塊 (lump), 塗 (smear/paint). When you see 土 on the left of a character, expect dirt, terrain, or a structure rooted in the ground.

Mandarin: tǔ, dipping 3rd tone. 土地 (tǔdì, land), 国土 (guótǔ, national territory), 土豆 (tǔdòu, potato — literally "earth bean"), 本土 (běntǔ, native/local). The adjective 土 colloquially means "rustic/old-fashioned" — calling someone's outfit 很土 means "very country bumpkin".

Japanese: on-readings ド (do) in 土地 (tochi, land — note irregular reading) and 土曜日 (doyōbi, Saturday); ト (to) in 土地 (tochi, again) and 国土 (kokudo). The kun-reading つち (tsuchi) is the everyday word for "soil" or "dirt".

Memory aid: a horizontal ground line with a small vertical mound + a top stroke — earth piled up. The character literally sits on its own ground.