[jevgeni]

They ARE pop-ups mostly. Just ones that are harder to block as compared to the 1990s pop-ups.

[kmoser]

Yep: devs call them "modals" while users call them "pop-ups" but they're the same thing.

Now, native browser modals (think Javascript's alert()) don't use the same underlying technology as HTML/CSS modals (think Bootstrap's modal component), but at the end of the day they're both modals/pop-ups.