Let’s talk a bit about whitespace and why I love it in design of all mediums. First, the definition:
From Wikipedia: 
In page layout,…[and increasingly, web design]…, white space is often referred to as negative space. It is the portion of a page left unmarked: margins, gutters, and space between columns, lines of type, graphics, figures, or objects drawn or depicted. The term arises from graphic design practice, where printing…generally use white paper. White space should not be considered merely ‘blank’ space — it is an important element of design which enables the objects in it to exist at all; …. Inexpert use of white space, however, can make a page appear incomplete.
Often, when I design, my clients comment “there is an empty space here, we should find something to fill it.” Oh, how I cringe when faced with this comment. On the web, specifically, there is a very limited amount of time that we have to grab the user’s interest in order to create the circumstances ripe for conversion. In this time, we need to direct their attention to our most valuable assets (calls to action, services, what we can do for them). So, the elements placed on a page need to have an explicit purpose. If we just add “something” to fill the space, what we are doing is removing focus from the important elements and, essentially, splitting the focus between something important and filler.
Whitespace also acts to give the eye a break. When a page is covered with text, images, ads, etc, there is no chance for the eye to rest and brain to receive the images. The effect we get is just an overwhelming blur of stuff. When I come across pages like this, I immediately get confused. I don’t know where to click, I don’t know what I was looking for and I certainly do not stay on the page very long.
Whitespace has numerable benefits. It draws attention to important elements. It makes those elements stand out on a page. It gives the eye and brain a chance to interpret the visual input. It also acts to create the feeling of sophistication, luxury, even grace. It helps to create order, balance, hierarchy. It improves readability and comprehension. It can grow your brand.
Whitespace is a vital principle of all design. It can not be discounted in achieving a successful communications campaign, whether that be in print or on the web. In the places where conversion rates are essential, whitespace is the key ingredient.