The purpose of the study is to confirm the Garmin ECG (electrocardiogram) software algorithm can detect and classify atrial fibrillation and normal sinus rhythm on single lead ECG data derived from a Garmin wrist-worn, consumer device. The study will also confirm the software's ability to create a Lead I ECG that is clinically equivalent to a reference device. The Garmin ECG software is not a diagnostic system and is intended for informational purposes only.

Inclusion Criteria:

• Able to read, understand, and provide written informed consent;
• Willing and able to participate in the study procedures as described in the consent form;
• Individuals who are 22 years of age and older;
• Able to communicate effectively with and follow instructions from the study staff;
• Have a wrist circumference that fits within the device band; and
• For subjects enrolled into the AF population, subjects must have a known diagnosis of AF and be in AF at the time of screening.

Exclusion Criteria:

• Physical disability that precludes safe and adequate testing;
• Mental impairment resulting in limited ability to cooperate;
• Subjects with a pacemaker or implantable cardioverter-defibrillator (ICD);
• Acute myocardial infarction within 90 days of screening or other cardiovascular disease that, in the opinion of the Investigator, increases the risk to the subject or renders data uninterpretable;
• Acute pulmonary embolism, pulmonary infarction, or deep vein thrombosis within 90 days of screening;
• Stroke or transient ischemic attack within 90 days of screening;
• Subjects taking rhythm control drugs;
• Symptomatic (or active) allergic skin reactions such as eczema, rosacea, impetigo, dermatomyositis, or allergic contact dermatitis on both wrists or over electrode attachment sites, including known allergy or sensitivity to silicone bands primarily used in wrist-worn fitness devices;
• Known sensitivity to medical adhesives, isopropyl alcohol, watch bands, or ECG electrodes;
• A history of abnormal life-threatening rhythms as determined by the Investigator;
• Significant tremor that prevents subject from being able to hold still;
• Women who are pregnant at the time of study participation; and
• Subjects enrolled into the SR population must not have any diagnosis of AF.