Red roots-what does "base" mean?

> I'm totally clueless! I just read the post from> December 3 entitled "Hair Red at the Roots"> - I, too, just applied a dark blonde (looks brown, but> that's what I wanted) permanent color and my roots> turned red! Someone said this is because the hair is> healthier at the roots. Anyway, someone posted to buy> a green ashe or a blue/green base and apply it to the> roots - WHAT DOES THIS MEAN??? How do I remedy> this????A green base will neutralize the red which should even out the color.This is a tricky one because you will probably need to pull it through the ends to match it.An ash blonde won't do the trick either because you've already lifted the roots an extra level.You really should let a stylist correct this.