The Sphere Grid is a character development system used in the video game Final Fantasy X. It allows players to customize their characters' abilities and stats by moving along a grid filled with various nodes. Each node represents a specific skill, ability, or attribute, and players can unlock these by earning Ability Points through battles. As characters progress, they can access new areas of the grid, enabling them to learn powerful abilities and enhance their stats. The Sphere Grid encourages strategic planning, as players can choose different paths for each character, tailoring their growth to fit individual play styles and team needs.