METAMAGIC
Some feats are labelled as being part of the MetaMagic feats category. These feats alter the very nature of magic itself, allowing the caster to change a specific aspect of a spell, or even unravel an opponent's spell. Metamagic feats like empower spell, maximize spell and others must be activated first, then they apply to the next spell cast. For instance, to cast an enlarged fireball, you would first type 'enlarge_magic' then cast the fireball spell, causing it to hit more targets than normal.
Metamagic like Counterspell or Primal Scar consumed a spell of your own to either halt or change an opponent's spell in mid-cast. These feats require you to consume a spell slot or spell at random of the appropriate spell level before executing.
See also: enlarge spell, empower spell, maximize spell, counterspell, primal scar