What is a modifier technically doing to make them Non-Destructive?

Hello Fellow Blenders,

I ask the question because when I look in at the outliner after adding a modifier to an object I see:
wrench and under the wrench I see the name of the modifier.

I do not believe modifiers are data-blocks. and if that is true, what is being attached to the object?
I guess it could be the children of the wrench could be technically called "automatic operations "?

any hint on what Modifier are and how they can be Non-Destructive would great help.

We all learn by sharing what we know

Its leaving the original data untouched and calculates his data operation on the fly passing the modified data instead of the original data.

Something like that what you already said. Usually there is some data which descriped the geometry ( → objects). Modifiers are just coded internal procedures to changes those data in a specific way ( → tools/wrench) . So they are nothing else as additional data.

@rigoletto @Okidoki Thank you for responding to my question about modifiers.
Sorry to take to so long to thank you.

Happy Blendering