Loading, advertising, whatever... a page that takes over when a pop-up is not called for... work carefully on this so they don't conflict
Problem
Solution
should be limited. If possible open to a restored previous session. Should have a loading status indicator.Should use visible and appropriate characteristics related to branding.
Variations
Loading screens - Try to avoid, only use if it really takes that long to load something. And usually (depends on the app) present the last stable things displayed.
In-process screens. When a delay is encountered inside an app/site/process, and the context change is so serious that presenting a loading pop-up would give the wrong impression (the old screen is gonna be wiped or is actually wrong).
Interaction Details
Presentation Details
Antipatterns