The Apple Watch Series 12 has recently launched, offering improved heart monitoring capabilities that set it apart from earlier models and its competitors. A new "Health Sensing System" includes more advanced sensors, enabling more frequent heart rate and heart rate variability measurements. These measurements are now taken every five seconds and every five minutes, compared to every five minutes and every two hours on the Apple Watch Series 11 and Ultra 3. This increased frequency allows for the measurement of two new heart rate variability indices and supports the "Vital Signs" feature during the day, collecting more reliable health data that may be used for future features related to health and longevity, such as Health Age. The Apple Watch Series 12 includes 32 electrodes, eight photodiodes, and more powerful green light sensors than the Series 11. In a test comparing the Apple Watch Series 12 with the Pixel Watch 5 and a Polar H10 chest strap, the Apple Watch was found to be slightly more accurate in tracking heart rate. The mean absolute error for the Apple Watch Series 12 was 1.9 beats per minute, compared to 5.3 bpm for the Pixel Watch 5. The Apple Watch also had a correlation coefficient of 0.998 with the Polar H10 chest strap, compared to 0.943 for the Pixel Watch. The performance gap between the devices became more noticeable during recovery phases. The Smart Stack feature of the Apple Watch includes Shazam, allowing the device to continuously listen to music and record the results in the Apple Music library. Users must activate this feature for it to be always on. The Apple Watch Series 12 is available in classic colors: light gold, night black, and silver, as well as a new dark bronze shade. It has the same battery capacity as the Series 11, providing about a day of autonomy. The revamped Health app will be available later this year. Many of the most interesting features of the Apple Watch, including the new Health app, Siri Recap, and Live Rewind, will be available by the end of the year. Users have found the Siri assistant to be faster and more responsive, and the tested health features indicate that Apple is setting a higher standard for measurable health parameters. Many of these new parameters are currently free, whereas competing devices charge for similar data.