different people say different things, but it stand for Independant Values. some people say inherited values, tho, but that's not right. xD when you catch/breed/obtain a pokemon it is assigned a number between 0 and 31 in each stat whatever the number is, it gets that many extra stat points in that stat. 0 is very bad, 31 is perfect. if you have a perfect 31 IV in a stat you get 31 extra points in that stat. ^^