Everyone here has a Skill Grid (like the one here {http://www.ffcompendium.com/h/faqs/ff10spheregrid.gif})
How you use it is up to you. This is how you up your stats on this site. With every level you gain certain 'Slots'. Our Special craftsman Cid will ask you for some Grid Spheres. How this works is you buy the number of spheres you need to fill up the slots and then once you level up that stat will be leveled.
So right now everyone has 2 slots. If i have a Magic Sphere and a Strength Sphere. Once I level Up I will have +1 MAG and STR x how many levels I went up.
Now each grid is different. Each class has a special stat level up-er for every 5 levels. Which means 1 special stat will auto-matically level up on a single Class. So instead of focusing on strength all the time. you can up your defense and agility while your Strengths level up automatically.
Here is the List of auto-ups:
+1 STR-
BEMA , BER , DK , FGHT , GUN , KGHT , MONK , PALA , SAM , SOL , WAR
+1 DEF-
BAR , RM , ONKNI
+1 MAG
BM , GEO , SCH , MKGHT
+1 MDE
BLM , CHEM, TM , SUM , WM
+1 AGL
DAN, NIN
+1 ACC
ARCH , DRA
+1 LUCK
GAM
+1 EVA
THI
+1 ALL
MIME
(why does the mime get all on every 5 level up? Because all of his/her stats are 1 so don't cry.)