Below the fold refers to the part of a webpage which can’t be seen without scrolling down.
Below the fold content is an issue for usability and conversion.
The "below the fold" issue is very important for conversion because sales points and calls to action placed below the fold may not be seen.
From a usability point of view it is an issue because it forces visitors to scroll down.
Fold management is complex because the fold placement in a webpage differs according to devices, screens and configurations.