ELI5: How fitness tracker devices count steps?

Imagine you have a tiny little bouncy ball inside your fitness tracker. This ball is connected to a code called an accelerometer.

Here's how it works in everyday life:

• Walking: When you walk, your wrist (where you wear the tracker) moves up and down and side to side. This movement makes the tiny ball bounce around inside the tracker.
• Accelerometer's Job: The code inside the accelerometer senses these bounces. It's like the code is saying, "Bounce! Then bounce again! Then bounce again!"
• Counting: The tracker's code counts how many times the ball bounces within a certain amount of time. Each bounce is recorded as a step. So, lots of bounces close together means you're walking quickly and taking lots of steps.
• Ignoring Bumps: The tracker is smart! It knows that not every bounce is a step. For example, if you just wave your hand around, it might ignore those bounces because they don't look like a normal walking pattern.
• Other movements: Some trackers use fancy code that can also detect when you're running, swimming, or even sleeping by looking at how the ball bounces.