white and black magic

I like viewing it in terms of intent. White magic has pure intentions, while Black magic is done out of cold-hearted malice. Grey fits somewhere in the middle- for example, a spell that knowingly causes negative effects to enact a greater good later on. Red magic is done out of passion- spells cast in anger especially, or any time one is overcome with emotion. Green magic is done in the interest of growth, ect.
This way makes more sense to me personally. A spell cast in good intentions is still white magic, even if it has unexpected negative consequences.

Of course it is a matter of "intention"! Evil people will use magic for evil intent. Magic itself is neither good nor evil. Only what it is used for.

What black, grey and white magick is truly a personal opinion.

There are so many versions of it, it can be quite confusing.

This is the simplest and probably the most accurate in describing them.

White magick believes in harming none and promoting free will.

Black magick believes in doing what you will.

Grey magick (although in some beliefs can be death as was pointed out) is generally used to describe a balance between both white and black based off of the best course of action decided by the practioner.

White magick if you summon an enitity (sorry but the word demon mean nothing to me) like Bael for asking knowleadge is white magick.
Black magick is if you summon the same entity for controlling people, winning the lottery, or inducing in love someone is black magick.
Magus choices.