180/90 rule to be explained please

Hi read this link

90 day rule

There are simple apps that you can use.

Put the previous travel dates in & it calculates the remaining days left.

I use this one.

https://ninety180.com/

Simple, none EU, only allowed to stay 90 days in 180 days, the new bio metric passport system in airports will log you on entering, and leaving.

Breach the 90 days, get a fine, breach the 180 days, automatic tax resident.