A seizure is a sudden, uncontrolled electrical disturbance in the brain that can cause changes in behavior, movements, or feelings. People experiencing a seizure may shake uncontrollably, lose consciousness, or have unusual sensations. Seizures can happen to anyone, but they are often associated with conditions like epilepsy. There are different types of seizures, ranging from mild to severe. Some may last only a few seconds, while others can last several minutes. It's important to seek medical help if someone has a seizure, especially if it's their first one or if it lasts too long, as this can lead to serious complications.