2. WILL SMARTWATCHES REPLACE TRADITIONAL WATCHES? 
Yes, smartwatches are likely to replace traditional watches. In fact, if you look around, you'll see that this is already happening. Many of the best-selling smartwatches are hybrid watches which look like traditional watches. Think Garmin Vivomove, Skagen Falster,Moto 360, and Withings Steel HR. So, smartwatch technology has already begun to infiltrate the traditional watch sector.
What's more, smartwatches are just as affordable (if not, more affordable) than traditional watches. You can pick up a smartwatch for under £100 ($130) these days. Also, you can charge it electronically, so there'll be no need to buy a replacement battery. That said, it seems very likely that smartwatches will replace traditional, battery-powered watches.
3. A smartwatch can work without a smartphone?
Yes.
Without Bluetooth connection to your phone, the smartwatch can still be used as an independent watch to check the time, calories burned, counting steps, distance run, etc. There's just no way to see more history and no way to get notifications from your cellphone.
The other is a cellular/LTE smartwatch that can be used independently without a phone. It can be connected to 2G, 3G, and 4G plug-in sim cards to use and can also receive and make calls, but the power consumption is relatively fast. You have to pay extra, and you have to insert a card just like a phone.

4. Can you make phone calls on a smartwatch?
Yes.
There are two ways to make and receive calls with the smartwatch. If it is a Bluetooth smartwatch, first download the App to your smartphone then connect. The mobile phone should not be too far away from the smartwatch, usually 1-10 meters, because of the distance limit of the Bluetooth signal. The other has a cellular/LTE connection, which allows you to make and receive calls directly without a smartphone, but requires you to choose a smartwatch with a smart card and pay a monthly fee.

5. Can I use smartwatches to take photos?
Yes, you can.
Taking photos is one of the most common features of smartwatches, which means: taking pictures with your smartphone controlled by your smartwatch. Most smartwatches on the market have this feature.
And many kids' smartwatches have HD cameras, but their power consumption is very quickly. You can take pictures independently with the smartwatch and keep them in your smartwatch.

6. Can smartwatches measure blood pressure?
Hypertension is one of the three common chronic diseases in human society. At present, smartwatches on the market claim to have blood pressure monitoring, but they are not very accurate. And smartwatch gets blood pressure data by PPG optical monitoring.

7. How does a smartwatch measure heart rate?
Most smartwatches monitor heart rate using PPG technology, which typically projects green light onto the skin hundreds of times per second and captures the light’s reflections. Since more light is reflected between heartbeats, this is a good indicator of heart rate (with the help of algorithmic software). The hardware used for PPG is often referred to as an "optical heart rate monitor."

8. How do smartwatches track steps and activity?
Most smartwatches use a "3-axis accelerometer" to count steps. This is hardware found in most smartphones, though the quality and accuracy of acceleration vary among smartwatch providers. Also, some watches have a gyroscope to measure direction and an altimeter to measure height.
Data collected from these sensors can be combined with other information from health apps to generate some health statistics - such as calories burned.

9. How does a smartwatch monitor sleep?
Most smartwatches can now monitor sleep. Through sensors that measure exercise and cardiovascular data (heart rate, heart rate variability, etc.).When combined, the data can be used to determine how much sleep you have and how much time you have spent in each of the four sleep "stages."
So smartwatches can not only monitor sleep duration but also sleep quality. There are smart health management companies that will analyze the data and give you periodic sleep reports to manage your sleep better.

10. How do smartwatches detect the stress level?
Smartwatches measure pressure by collecting HRV data and combining it with algorithms. Stress is a mixture of physical and psychological symptoms.

11. Can I use smartwatches to play music?
Yes, you can.
Many smartwatches now play music on your Bluetooth headset. You can listen to your phone via Bluetooth or choose a smartwatch that can store songs like an MP3.

12. Can I change the smartwatch strap by myself?
Yes, you can, and very easy.
Most smartwatches are free to change the strap, so you can keep your smartwatch clean and fresh for a long time. According to different occasions and clothes, you can choose different colors and styles of the strap, and very simple.

13. How long will smartwatches work after fully charging?
Generally, it can be used for 1-30 days after a full charge. This depends on how many monitoring modes the user has enabled and how often they use them.GPS and video calls are the most power-hungry.