The traditional plate-format meal — a central serving of rice or bread surrounded by small bowls (katori) of vegetables, lentils, yogurt, and sweet, meant to balance every taste in a single sitting.
खान-पान · Khan-Pan
A thali is built around the classical idea of shad rasa, the six tastes, sweet, sour, salty, bitter, pungent, and astringent, aiming to include something from each category so the meal itself is considered balanced by Ayurvedic reasoning, not simply filling.
Regional thalis vary enormously in exact composition, a Gujarati thali leaning sweeter, a South Indian thali built around rice, sambar, and rasam served on a banana leaf, a Rajasthani thali heavier and richer, but the underlying principle, several small dishes eaten together rather than one large plate, holds across nearly all of them.