From people who just want to be more active throughout their day, to those who work out a few times a week, to athletes committed to improving their performance.

Apple Watch brings together the capabilities of an all-day fitness tracker and a highly advanced sports watch in one device you can wear all the time.

It can track a wider variety of activities because it's able to collect more types of data.

It uses an accelerometer to measure your total body movement.

It has a custom sensor that can measure intensity by tracking your heart rate.

And it uses the GPS and WiFi in your iPhone to track how far you've moved.

We wanted to give you the most complete picture of your all-day activity,

and not just highlight the quantity of movement, but the quality and frequency, as well.

So the Activity app on Apple Watch measures three separate aspects of movement, with a goal of helping you sit less, move more, and get some exercise.

The Move Ring measures the calories you've burned that gives you the best overview of how active you are.

The Move Ring is customized to you, and you close it when you hit your personal calorie goal for the day.

The Exercise Ring captures the brisk activity that you've done.

This doesn't necessarily mean hard-core exercise. It means any activity done at the level of a brisk walk or above.

You close the ring when you hit the globally recommended 30 minutes of exercise per day. And it doesn't even need to be all at once.

The Stand Ring shows how often you have stood up to take a break from sitting, which helps you minimize your sedentary time.

And this may seem like a small thing, but sitting less can go a long way towards improving your health.

A complete ring means that you have stood for at least one minute in 12 different hours during the day.

There's also a dedicated Workout app to provide more detailed measurement when you need it most.

You can select your workout from a list of popular activities.

Then set a goal based on how long you want to work out, the number of calories you want to burn, or the distance you want to go.

And during your workout, you can see in a glance, how far, how fast, and how long you've been at it.

When you're done, you can end your workout, see an entire summary of your session, and earn awards for your achievements.

The Fitness app on the iPhone stores all your activity data, and lets you see your workout history whenever you want.

It also shares your data with the Health app, where it can be accessed by health and fitness-related third-party apps.

Over time, Apple Watch actually gets to know you the way a good personal trainer would.

It's designed to deliver intelligent reminders to keep you motivated and on track.

And it can suggest goals that are personal, realistic, and, most important, achievable, which gives you a far better chance of succeeding.

Apple Watch is going to greatly improve the way we keep track of our activity, and change the way we look at fitness.

We think it's going to help a lot of people live a better day and a healthier life.