Lazy loading: set of techniques to make (some) content on web pages load only when actually needed (eg. visible on screen):

Lazy loading: set of techniques to make (some) content on web pages load only when actually needed (eg. visible on screen):
* https://en.wikipedia.org/wiki/Lazy_loading
* https://developer.mozilla.org/en-US/docs/Web/Performance/Lazy_loading
The concept is generic and can applied to anything, applying to specific things obviously has different ways and requirements.