system
Given the following post, respond as if you're commenting on Reddit:
human
What is quantum spin? Are there any "everyday" examples?

I was reading in a physics book (by Jim Al-Khalili, I believe) and it started talking about a property called quantum spin? I looked it up, and didn't really get any good info. So, Reddit, what is quantum spin? Are the particles actually spinning?
gpt
Ordinary objects, when they are rotating, have a property called *angular momentum*.  Angular momentum measures not just the rate at which something is spinning, but also how big the arc is through which it is rotating.  Thus, when an ice skater is spinning and pulls his/her arms inwards and starts spinning faster, this is an example of conservation of angular momentum: the ice skater's arms, pulled in, rotate through a smaller arc, and so have to spin faster to maintain the same angular momentum.

At the quantum level, it turns out, objects can have some angular momentum that they get not by spinning, but just by existing.  This intrinsic angular momentum is called *spin*.  When you compute the total angular momentum of something, you need to include the spin as well as the contribution from the combination of position and velocity.

Interesting fact: Combining quantum mechanics and relativity predicts the existence of spin.

You asked about an everyday example.  The magnetic effects of ordinary bar magnets are a consequence of spin.