Atrial fibrillation (AFib) is a type of arrhythmia, or irregular heartbeat, that affects the normal rhythm of the heart. It occurs when the electrical signals in the atria, the upper chambers of the heart, become chaotic and cause the atria to contract rapidly and irregularly, rather than in a coordinated manner.

In AFib, the heart beats in an irregular and often rapid fashion, which can lead to a reduced blood flow from the heart to the rest of the body. This can increase the risk of blood clots forming in the heart, which can lead to stroke, heart attack, or other cardiovascular complications. AFib can also cause symptoms such as fatigue, shortness of breath, chest pain, or palpitations.

AFib can be temporary or persistent and can be caused by various factors such as age, high blood pressure, heart disease, overactive thyroid gland, or excessive alcohol consumption. It can be treated with medication, lifestyle changes, or medical procedures such as electrical shock, catheter ablation, or heart surgery.

In summary, atrial fibrillation is a common heart rhythm disorder that can lead to serious cardiovascular complications and is treated with a combination of medications, lifestyle changes, and medical procedures.