Calling stats experts ofr a question regarding z table and normal distribution

A beginner question but I would like to understand this. I'm studying normal distribution and probability and would like to know where the values in the [z table](https://www.ztable.net) come from and how they are calculated. All sites I see just link to the table but none show how the values originate.

P.S. Also forgot how to add a link properly. Can someone show me how it's done