Smartwatches track heart rate, steps and sleep reasonably well — but not precisely enough for medical use. Here’s what you can and can’t trust.

Most smartwatches are water resistant, not waterproof — and the difference matters. Learn what IP67, IP68 and ATM ratings actually mean before you swim.

Smartwatches track heart rate and flag irregular rhythms, but can’t diagnose a heart attack. Here’s what ECG alerts can and can’t actually tell you.

Smartwatches emit non-ionizing Bluetooth radiation — far lower than a phone. Current research shows no evidence linking them to cancer. Here’s what scientists say.