"System" -- any bloody thing you care about, any collection of mass and energy.

"Optimize" -- to constrain the system to within a subset of its state-space. Or in other words, to make only some things happen rather than all other possible things.

Generally, as long as something is physically possible, you can spend some amount of energy to make it reasonably probable or unreasonably improbable. This may just be far more energy than you happen to have, or care to spend.