Muggle
From Harry Potter Wiki
Muggles are people who are incapable of magic, and who are usually unaware of the Wizarding World. Muggles are not to be confused with Squibs. Squibs are people of magical families with no true magical power themselves.
There are many differences between the Muggle world and the wizarding world. These differences extend beyond magic. Muggles and wizards have a different currency system.
The International Statute of Wizarding Secrecy keeps the Muggle world unaware of the wizarding world. Muggles are generally either afraid of magic or belive magic to be silly and childish. Magic may be hidden from Muggles with Muggle-Repelling Charms, or by forcing witnesses to forget what they saw through an Obliviate spell.
The Dursleys are Muggles who looked after Harry Potter during the summer school holidays. They are related to Harry, but would rather not be because of their "very medieval" attitude towards magic.
Arthur Weasley is very interested in how Muggles function without the aid of magic. As an employee with the Misuse of Muggle Artifacts Office, his shed at The Burrow is full of Muggle items which he finds fascinating. He has a large collection of batteries and electric plugs. As Hermione Granger's parents are both Muggles, he was ecstatic to meet them in 1992, and invited them to have a drink at The Leaky Cauldron. During Harry's stays at The Burrow, he likes to sit next to Harry, in order to ask questions about Muggles. He is also interested to learn how the Muggle post office and a telephone work.
Though a Muggle-born witch herself, Hermione took up Muggle Studies at Hogwarts School of Witchcraft and Wizardry because she wanted to learn about Muggle life from a witch's perspective.
Some pure-blood families, such as the Malfoys and the House of Black, hate Muggles. Lord Voldemort and his Death Eaters killed Muggles for amusement. At one time, Araminta Meliflua proposed a Ministry of Magic measure to make Muggle hunting legal. Such wizards refer to Muggle-borns as Mudbloods.
