It’s called “above the fold”.
It’s what you see when you land on a page before the first scroll.
It determines if the visitor has a good or bad impression.
Will they stay?
Or will they go and look for another solution to the problem you can solve.
It takes 50 milliseconds to form an impression about a website. (Source: Attention Web Designers: You Have 50 Milliseconds to Make a Good First Impression!” published in the journal Behavior & Information Technology in 2006.)
That is one-fifth of a second.
Most businesses don’t have an optimized “above the fold”.
Creating confusion that pushes potential clients away and to their competition.