Because your magic flows from within you, you can alter your spells to suit your needs; you gain two Metamagic options of your choice from the "Metamagic Options" section later in this class's description.
You can use only one Metamagic option on a spell when you cast it, unless otherwise noted in one of those options.
Whenever you gain a Sorcerer level, you can replace one of your Metamagic options with one you don't know.