Apparition is a magical practice where a wizard or witch can transport themselves from one location to another. The process of Apparition is supremely difficult, and an exam must be passed for those wishing to do it. There are a number of rules and complications that come with this magic. For example, if a witch or wizard Apparates incorrectly, they risk 'Splinching' themselves, where parts of their body transport to other places. This can be mild (such as leaving half an eyebrow behind) or catastrophic, such as separating themselves from full limbs. There are also rules around where you can Apparate to and from. Famously, you cannot Apparate in or out of the Hogwarts grounds.