Any page on a website has two parts 'Above the Fold' or 'Below the Fold'.
Above the Fold is everything that is visible when your page first loads and before your visitor starts scrolling. Below the Fold is everything else.
Above the Fold is the once chance you have to keep a visitor. If they don't see anything of value there then they are highly unlikely to scroll or take any further action ... they are far more likely to just hit the back button.
What Above the Fold means varies depending on the device. A visitor using a smartphone to view a page on your website sees far less 'Above the Fold' than a visitor using a laptop or desktop computer.
In SEO, therefore, what you present Above the Fold is crucial to reducing pogo sticking and bounce rates. Its also vital that your Above the Fold content loads fast so your visitors see something quickly (they are assured your website is working) and are immediately engaged - Below the Fold can load later.
So we generally have four pieces of work here:
Note, as with so much Search Engine Optimization, we might often have to weigh up improving one area with degrading others.
For example, Lazy Load (a way to delay loading images 'Below the Fold') sounds good. Images are one of the biggest drags on page loading speeds and Google is all about handing out brownie points to content which loads lightning fast.
In this case we would have to weigh up the advantages of faster loading speeds (would it actually have any effect on rankings anyway) versus Google not indexing some of our content until who knows when.
I'm Tim Hill, a Search Engine Optimization and Online Marketing specialist. I created this site to help others understand that SEO is not a mysterious black art!.
If your a newbie try the Getting Started in SEO page, otherwise feel free to dig around and learn more.