What condition is characterized by a fast heart rate?

Tachycardia is defined as a condition where the heart rate exceeds the normal resting rate, typically considered to be over 100 beats per minute in adults. This elevated heart rate can occur in response to various factors, including stress, anxiety, fever, anemia, or heart-related issues. It is important to recognize tachycardia not only as a standalone condition but as a symptom that may indicate underlying health issues requiring further evaluation or treatment.

In contrast, bradycardia refers to a slower than normal heart rate, while arrhythmia covers a broader category of irregular heartbeats, which can include both fast and slow rhythms. Atrial fibrillation is a specific type of arrhythmia characterized by a rapid and irregular heartbeat, but it falls under the larger umbrella of arrhythmias rather than being specifically defined as a fast heart rate by itself. Thus, tachycardia accurately identifies the fast heart rate condition referenced in the question.