The fold. If you're a web developer, you've heard it mentioned plenty of times. Often, a client will throw the word out, having heard it somewhere in a designy context and wanting to see if it makes them sound informed. What does it mean and does it apply to web design here in 2015?
You would think the response is quick and simple, but this is a very complicated, very debated topic. Go ahead and Google it! If you do, you'll see there is a pretty even split of people who are for and against designing with the fold in mind.
Back to the question: what is the fold? Well, the fold is a term borrowed from the print world. Newspapers put the most compelling, biggest stories front and center. Because a newspaper is folded in half, the hottest real estate is the top half of the paper - it is the portion of the paper that is sure to be seen. Content that causes a passer-by to pick up and read on takes precedence above all else. Sure, it's a print term but it is a concept that absolutely applies to web design. In the web world, the fold would be the bottom of the visible area, the space initially visible before a user has to scroll.
Here's the point of contention. If the fold exists online, how do we deal with the placement of our content? Do we cram everything important up top? What is the most important content? Do we even allow anything to be visible only upon scrolling? Can we even count on what is visible for a user based on the fact that they could be viewing a page on any number of devices? Oh, so many questions!
Honestly, a book could be written on the topic. Several have. All this to say, yes the fold is an extremely important consideration in the layout of your site, but no, you should not try to avoid counting on users to scroll. Don't be afraid of scrolling! This is 2015. The vast majority of available data supports the notion that scrolling is commonplace and expected. Make educated decisions about the content that is of the most importance...develop a list of goals for a page and organize your content accordingly. The length of a page should be determined by what it is going to take to lead a user through a conversation with an actionable outcome. "Dear user, here's what I want you to know, and here's what I want you to do."