Characters skill and attribute developement in FFX is conducted exclusively on the Sphere Grid. Characters will not grow in power simply by defeating enemies as in previous Final Fantasy games, so you must understand the basics of the Sphere Grid in order to strengthen your characters.
Character Developement Flow Chart
Characters Earn AP (Ability Points) after defeating an enemy in battle. Certain enemies also surrender spheres, which are used to strengthen your characters >>
When a characters AP reahces a certain limit, his or her sphere level will increase >>
The character can thne move a certain number of spaces on the Sphere Grid equal to his or her current sphere level >>
Activate nodes on the Grid using thier corresponding spheres in order to raise attributes and teach new abilities.
The Sphere Grid
When you select the Sphere Grid from the Main Menu it will bring up a screen, that is the Sphere Grid. Press the X button to display the command window. Choose Move if you wish to move that character around the Grid. When you select Move, the illuminated circles indicate how far you can move based on your current sphere level. Choose Use if you wish to use a sphere to activate a node. Selecting Use will open a new window showing all the spheres currently in your possession. You can only use spheres that correspond to a nearby node, highlighted in a while. Place a sphere into its corresponding node to learn the ability availible there. In addition to the node at the characters current posistion, you can activate any adjacent nodes without moving to them.