Curses

Curses are the worst kind of magic, intended to affect the target in a very negative manner. 

The three Unforgivable Curses, are, as heard in the name, unforgivable. No wizard should use them ever, unlike hexes and jinxes that can be used for good sometimes. But they're obvioulsy still used by Dark Wizards, who don't care about laws.

Cruciatus Curse

One of the Unforgivable curses, also known as the Torture Curse. It inflicts horrible pain on the victim, and if the victim is exposed to the curse for too long, they will go insane. As happened with Alice and Frank Longbottom, who couldn't even recognize their own son after being tortured By Bellatrix Lestrange. If the caster uses the curse on a human being, they will receive as punishment a lifetime in Azkaban. The only exception to this is if there is proof of the caster being under the influence of the Imperius Curse; an example of this is Viktor Krom using the Torture curse on Cedric Diggory, while being under the Imperius Curse by Barty Crouch Jr (disguised as Alastor Moody).

To succeed to cast the curse, one shall really desire to inflict this pain on the victim. An example is Harry Potter casting the curse on Bellatrix after her killing Sirius Black. His curse was successful, but only for a very short amount of time, as he didn't have the sadistic traits a wizard needs to use the curse efficiently. 

Incantation: Crucio (KROO-see-oh). It means 'I torture' in Latin.

Hand movement: Canonically unknown. My headcanon is that it's similar to the Imperius Curses; you point your wand at the victim.

The charm does not produce any light.

Imperius Curse

Another one of the Unforgivable Curses. It allows the caster full control over the victim. A wizard with very strong willpower could resist this curse, but that is highly uncommon to happen. As an Unforgivable Curse, it was the same punishment as the Cruciatus Curse above.

Incantation: Imperio (im-PEER-ee-oh). The name comes from he Latin word 'Imperium' which means 'power' or 'authority'.

Hand movement: Point your wand at the victim.

This curse produces no light.

Killing Curse

The Killing Curse causes an instant and painless death to the victim. It leaves no trace on the body. It's the worst out of the Unforgivable Curses, and if used, the caster receives a lifetime in Azkaban prison.

Incantation: Avada Kedavra (a-VAH-dah ke-DAH-vra). 'Avada Kedavra' comes from Armaic, and means 'let the thing be destroyed'.

Hand movement:

The curse produces a green ray of light when used.

Some other, not near as bad curses included:

Slug-vomiting Charm/Curse

Alot of Dark Charms are not 100% in only one category. The slug-vomiting charm, that is seen as a curse, would by me be put in the hexes category instead, since it's not near as bad as the rest of the curses, and the effect wears off after a time. But usually it's up to one own to categorize them how you like. 

The Slug-vomiting Charm makes the victim vomit slugs uncontrollably. It wears off by itself after a while, but another cure for it is Treacle Fudge.

Incatation: Slugulus Eructo (slug-YOU-lus eh-RUCK-toe). 

Hand movement:

The charm produces green light.

Full Body-Bind Curse

This curse temprarily paralyzes the victim.

Incantation: Petrificus Totalus (pe-TRI-fi-cus to-TAH-lus).

Hand movement:

It produces white, purple, or yellow light.

Jelly-Legs Curse

This curse makes the victims legs wobbly and unstable; like wet spaghetti. It is categorized as both curse and jinx.

Incantation: Locomotor Wibbly (LOH-koh-moh-tor WIB-lee)

Hand movement:

The curse produces orange light.

Leg-Locker Curse

The curse 'locked', bound, the victims legs together like an invisible rope.

Incantation: Locomotor Mortis (LOH-koh-moh-tor MOR-tis).

Hand movement:

It produces red or purple light.

Tounge-tying Curse

The curse ties the victims tounge in a knot. Useful in duels, since the victim can't speak properly, thus he can't say the incantations for the spells he's trying to cast.

Incantation: Mimblewimble (MIM-bull-wim-bull)

Hand movement:

This curse produces blue or purple light.

Hair Loss Curse

This curse removed the victims hair.

Incantation: Calvorio (cal-VOR-ee-oh).

Hand movement: Canonically unknown. My headcanon; An upside down 'T'. First a downward slash, and then a line at the bottom of the downward slash.

It produces red or purple light.