The Summoning Charm is a spell used to summon an object to the caster, using the incantation Accio. When the witch or wizard knows what the object they are after is they will usually name it as part of the spell, for example: "Accio dictionary". The spell with the opposite effect is the Banishing Charm.
/ˈæki.oʊ/ ak-ee-oh – film and video game /ˈæksi.oʊ/ ak-see-oh – U.K. audio book /ˈæsi.oʊ/ as-see-oh – U.S. audio book
 Effects and Limitations
The spell requires the caster to concentrate on the object as well as to speak the incantation. If the witch or wizard isn't concentrating enough the spell wont work and objects either wont move at all or will give up partway through. If the concentration is great then the spell can be used over a quite a distance. Sometimes the user of the spell does not need to know exactly what they are summoning, a general idea is sufficient, such as knowing a sweet is hidden somewhere if not what type of sweet or precisely where it is.
 Uses in the books
 Fourth Book
Molly Weasley used Accio in the summer holidays in 1994, when her twin sons Fred and George were trying to smuggle their magical sweets out of the house to help with their ambition of running a joke shop (which Molly did not approve of). She kept using the spell over and over until she'd found all the sweets that were hidden on their persons.
Harry Potter was taught the Summoning Charm in Charms Class by Professor Flitwick, however Harry was too worried about the First Task in the Triwizard Tournament to be able to concentrate on it and was given extra homework on the subject. Harry was given a hint by his Defence Against the Dark Arts teacher that a Summoning Charm would help him as he could summon his Firebolt and fly around the dragon his would face. Hermione Granger spent a day teaching Harry how to cast the spell properly and finally Harry mastered it.
During the task Harry successfully summoned his broom from the boy's dormitory in Gryffindor tower to an enclosure by the Forbidden Forest. This impressed Flitwick. Harry's friend Ron Weasley was all for him using the same spell again in the Second Task so he could use aqualungs underwater, however Hermione pointed out that this would risk the exposure of the wizarding world to Muggles.
When Harry was trapped by Death Eaters and about to be killed by Lord Voldemort, Harry jumped over a Portkey that could take him to safety in Hogwarts to get to Cedric Diggory's body in order to bring it back with him, seemingly at the cost of going back at all. However just in time Harry was able to summon it to him and he managed to take both himself and Cedric's body back.
 Fifth Book
Fred and George had their brooms confiscated by Dolores Umbridge after a Quidditch match. When the twins made their escape and quit Hogwarts, they summoned the brooms from her office, where they had been chained to the wall. Their spells were powerful enough to take the chains complete with pegs with them as they zoomed to their owners.
Bellatrix Lestrange tried to summon the Prophecy from Harry's hands when they were in the Department of Mysteries, however Harry was able to block her with a Shield Charm. Hermione also summons their wands when they are Disarmed. Also Ron Weasley when under a spell that was making him act oddly managed to summon a brain to him from a tank, which consequently attacked him.
 Sixth Book
When Draco Malfoy uses Petrficus Totalus on Harry whilst on the Hogwarts Express, he tries to summon his wand into his hand non-verbally. It doesn't work, though this isn't surprising as he hadn't been taught to cast Non-Verbal Spells yet.
After Harry and Albus Dumbledore find the cave where one of Voldemort's Horcruxes is hidden, Harry suggests simply summoning it. Dumbledore agrees, realising that this would be a good way of seeing what defences are activated in the event that someone tries to steal the Horcrux. The spell fails to summon it, but reveals that Inferi are hidden in the lake. Shortly afterwards when Madam Rosmerta offers to run and get her brooms so that Harry and Albus Dumbledore can get to Hogwarts castle after the Dark Mark is seen over it, Dumbledore tells Harry to summon them instead.
 Final Book
Harry Potter and Rubeus Hagrid were fleeing from Death Eaters on Sirius' flying motorbike when Hagrid jumped off in order to stop one of them from cursing them. He landed on the Death Eater's broom, which fell under their weight. Harry in his desperation tries to summon Hagrid to him, but with Hagrid's part-giant blood the spell didn't work.
Hermione reveals that at the end of the last school year when packing her trunk she realised that Dumbledore would have had books on Horcruxes, and was able to summon them from Dumbledore's office into the girl's dormitory. She theorises that Dumbledore would have wanted them to be found, or else he would have protected them from the spell.
When Harry turns 17 and is legally allowed to use magic outside of school, he celebrates by using his first legal magic whilst of age and summons his glasses to him, and they poke him in the eye. When Harry attends a wedding the next day he uses a Polyjuice Potion with hair that Fred had summoned from a local Muggle boy.
After the trio realise that the Locketcrux had been in Number 12, Grimmauld Place Hermione tried to summon it, though they keep looking in case it was magically protected. They later realise it isn't there. Harry tries the same again in Dolores Umbridge's office. 
- ↑ J. K. Rowling, GoF 15
- ↑ 2.0 2.1 J. K. Rowling, GoF 20
- ↑ 3.0 3.1 J. K. Rowling, GoF 5
- ↑ 4.0 4.1 J. K. Rowling, OotP 35
- ↑ 5.0 5.1 J. K. Rowling, DH 10
- ↑ J. K. Rowling, GoF 18
- ↑ J. K. Rowling, GoF, 22
- ↑ J. K. Rowling, GoF 26
- ↑ J. K. Rowling, GoF 34
- ↑ J. K. Rowling, OotP 29
- ↑ J. K. Rowling, HBP 8
- ↑ J. K. Rowling, HBP 26
- ↑ J. K. Rowling, HBP 27
- ↑ J. K. Rowling, DH 4
- ↑ J. K. Rowling, DH 6
- ↑ J. K. Rowling, DH 7
- ↑ J. K. Rowling, DH 8
- ↑ J. K. Rowling, DH 13
- ↑ J. K. Rowling, DH 17
- ↑ J. K. Rowling, DH 26