Notes

1. Jinx: Minor dark magic; spells whose effects are irritating but amusing, almost playful and of minor inconvenience to the target.
Hex: Consistently affects the object in a negative manner; has a connotation of dark magic, but more so than a jinx. Major inconvenience to the target.
Curse: The worst kind of dark magic, intended to affect the target in a strongly negative manner.
2. Anti-Disapparition Jinx: Prevents Disapparition within a certain area
Anti-intruder jinx: Repels intruders
Pimple Jinx: Boils erupt
3. Hexes can be used in a defensive capacity. For instance, in 1996, Ginny Weasley gained a reputation for being an accomplished caster of the Bat-Bogey Hex after using it to free herself from Dolores Umbridge's Inquisitorial Squad and also for casting it on Zacharias Smith from her carriage on the Hogwarts Express.
4.The Unforgivable Curses are three of the most powerful and sinister spells known to the wizarding world. They are tools of the Dark Arts and were first classified as "Unforgivable" in 1717, with the strictest penalties attached to their use. The three curses consist of the Killing Curse (Avada Kedavra), Cruciatus Curse (Crucio), and Imperius Curse (Imperio).
By the 1990s, using any of these three curses on another human being, Muggle or wizard, would result in a life sentence to Azkaban, unless there was sufficient evidence that the caster did so under the influence of the Imperius Curse. Aurors were permitted to use them during the First Wizarding War, and during the height of the Second Wizarding War under Lord Voldemort's regime, the curses were made legal, though this was presumably repealed following Voldemort's demise.
(Avada Kedavra) Description: Causes instant and painless death.
The incantation of Avada Kedavra causes a blindingly intense green bolt of light to shoot from the end of the caster's wand, which, on contact with the victim, results in instant death. There are no secondary effects; the victim simply "drops dead" for no biological reason. It is possible that the victim's internal organs cease function. However, it seems to be more likely that the method of killing is due to the soul of the victim being magically ripped from their body. Evidence for this comes from the testimony of perhaps its most prolific caster; Lord Voldemort. Having experienced the lethal effects of a rebounded Killing Curse but surviving due to his creation of multiple Horcruxes, Voldemort described the sensation of being struck by it as having his consciousness torn from his body, accompanied by a sensation which he described as being "pain beyond pain". Muggle coroners would be unable to find a cause of death in such an attack, but the Ministry of Magic recognises the signs of the curse.
The Killing Curse has no counter-curse and cannot be blocked by magical means. However, the green energy bolt may be dodged or blocked with a solid object. For instance, Albus Dumbledore once transfigured a statue from the Fountain of Magical Brethren to shield Harry Potter from Voldemort's Killing Curse during the Battle of the Department of Mysteries. If the curse misses the victim and strikes an inanimate object instead, it may cause a small explosion at the point of impact results, which may start a fire of green flame. However, the curse may also ricochet off the object in question.
The Killing Curse was used regularly by Lord Voldemort, possibly more than any other spell, and his Death Eaters used it as well. The spell is performed verbally as a rule; Bellatrix Lestrange killed a fox with a non-verbal spell after Apparating with Narcissa Malfoy at Spinner's End, thinking that it was a lurking Auror, but it is unknown whether it was Avada Kedavra or some other lethal curse.
Only two people have ever been able to overcome the effects of this curse: Harry Potter, who was given magical protection against Lord Voldemort's use of the curse through his mother's loving sacrifice and Voldemort himself due to his Horcruxes, which each have part of himself in them. Harry was later saved by the effects of Priori Incantatem when his and Voldemort's wands locked during a duel in 1995. When Voldemort struck him with a Killing Curse again in 1998, Harry was able to survive once again because Voldemort had taken some of Lily Potter's protection of Harry into his own body by using Harry's blood in his rebirth ritual in 1995. This process somehow tethered Harry to life so long as Voldemort himself was alive.
In 1996, Fawkes sacrificed himself by swallowing a Killing Curse that Voldemort aimed at Dumbledore. It killed him as it would anything living, but in a typical display of a Phoenix's response to death, he burst into flames and was immediately reborn from his own ashes.
Lord Voldemort murdered many people with this curse: his father, his grandfather, his grandmother, James Potter, Lily Potter, Charity Burbage, Frank Bryce, Gellert Grindelwald, Bertha Jorkins, three goblins, and likely many more.
(Crucio) Description: Inflicts excruciating pain on the recipient of the curse (tortures them).
The Cruciatus Curse, which inflicts excruciating pain upon the victim, requires the verbal incantation and the use of a wand. The effects of the curse depend upon the desires and emotions of the character — to produce the excruciating pain implied by the name, one must, according to accomplished caster Bellatrix Lestrange, desire to cause pain purely for its own sake. The extreme pain inflicted by the curse makes it uniquely suited as a form of torture, and was used regularly by the Death Eaters.
When Harry Potter was made the victim of the curse in June 1995, he described it as feeling like his head was being split open while having his bones set on fire. However, since this is the only time Harry is known to have been inflicted with the Curse, and as no one else has ever given a description of its effects, it is unknown if this is how the Curse always feels.
The Cruciatus is the curse which caused Alice and Frank Longbottom such suffering that they were admitted to the permanent ward at St Mungo's Hospital for Magical Maladies and Injuries as cases of insanity. This was carried out by: Barty Crouch Jr, Bellatrix Lestrange, Rodolphus Lestrange, and Rabastan Lestrange.
(Imperio) Description: Causes the victim to perform the unquestioned bidding of the caster.
The Imperius Curse places the victim in a trance or dreamlike state, leaving him or her under the complete control of the caster. The experience is described as a "wonderful release" from any sense of responsibility. The victim is calm, from doing things they would be physically incapable of otherwise, to committing horrible crimes, and they obey any order. For example, Barty Crouch Jr, while disguised as Alastor Moody, had Draco Malfoy perform a series of astonishing flips, as a Ferret, under the Imperius Curse. It is also seen that the curse works on animals, as he also casts the Imperius Curse on a spider during class.

Death Eaters have made use of this curse; for instance, in forcing Broderick Bode and Sturgis Podmore to try to steal a prophecy from the Department of Mysteries and to place several officials under their control to facilitate their take-over of the Ministry of Magic in 1997. Many Death Eaters also claimed to be under the Imperius Curse during the First Wizarding War to avoid imprisonment in Azkaban.

Resisting the Imperius Curse is possible, but extremely difficult. Only those of a particularly strong will can achieve it. Harry Potter, Barty Crouch Snr and Barty Crouch Jr each learned to resist the curse after being subjected to its effects. Harry Potter in particular appeared to be extraordinarily good at this, as he was able to partially resist the curse from the very first time it was ever cast upon him, and he was later able to completely resist it when it was cast upon him by Voldemort himself.