Focus

Focus affects spells differently from the wand movement or incantation.

a component that is not present in every spell.

the Levitation Charm and the Locomotion Charm, require you to focus on
the target you are casting the spell upon and also focus upon the effect
you are intending to produce.

you cannot avoid it if a spell requires it.

The hardest part of successful focusing is that your mind must be relatively clear at the moment you are casting a spell.

The Severing Charm (Diffindo)

relies most heavily upon your ability to focus. The charm not only needs
to be targeted specifically, but factors such as depth must be taken
into account.

not very effective when used against animated, living things, making it an impractical dueling spell.

The Softening Charm (Spongify)

example of focus because there are no major backfires if it is done
improperly. If you do not focus correctly, you might accidentally soften
the wrong thing, but it will right itself quickly enough. The effects
of this charm are temporary.

Midterm!