Why can multiple websites share port 80 on the IIS server?

Why can so many websites share port 80 on the IIS server? doesn't it mean that only one website can use port 80 on one machine, but I found on this server that, A lot of websites share port 80. do you understand that a service process uses port 80 instead of a website? a service process can have N virtual websites, why can so many websites share port 80 on the IIS server?
Isn't it true that only one website can use port 80 on one server? but I found that many websites share port 80 on this server. I am wrong.

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A service process uses port 80
Instead of a website
A service process can contain N virtual websites
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Port 80 is used to access iis services externally.
The iis service has a virtual host .. Then access the host through this