
White space is exactly what you think it is, the empty space around the words on a page, more specifically the space between paragraphs.
We are used to applying and understanding white space in poetry.
Poetry, by Marianne Moore
I,
too, dislike it: there are things that are important beyond all this fiddle.
Reading it, however, with a perfect contempt
for it, one discovers in
it after all, a place for the genuine.
Hands that can grasp, eyes
that can dilate, hair that can rise
if it must, these things are
important not because a
high-sounding
interpretation can be put upon them but because they are
useful. When they become so derivative as to
become unintelligible,
the same thing may be said for all of us,
that we
do not admire what
we cannot understand: the bat
holding on upside down or in quest of
something to
eat,
elephants pushing, a wild horse taking a roll, a tireless wolf under
a tree, the immovable critic twitching his
skin like a horse that feels
a flea, the base-
ball fan, the statistician--
nor is it valid
to discriminate against 'business
documents and
school-books';
all these phenomena are important. One must make a
distinction
however:
when dragged into prominence by half poets, the result is not
poetry,
nor
till the poets among us can be
“literalists of
the imagination”—above
insolence and triviality and can
present
for
inspection, 'imaginary gardens with real toads in them', shall we
have it. In the meantime, if you demand on
the one hand,
the raw material of poetry in
all its rawness and
that which is on the other hand
genuine, you are interested in
poetry.

White space is a visual rest for the reader, a break in the long line of text, but it is not arbitrary. It is the marriage of narrative content to visual appeal. The dance of what it expressed in the story and what is excluded. White space is often the visual representation of what was left unsaid in the scene. Sven Birkerts says it this way, "I feel like a downer suggesting that limit, constraint, and the compulsions of the unknown - the excluded - are the true foundation of narrative art. So much art is a matter of calculated emptiness -gaps- that excite the reflective sensibility."
White space acts as a gavel of sorts, adding weight and meaning to the last word in a paragraph. In his books Orality and Literacy, Walter Ong argues that print "both reinforces and transforms the effects of writing on thought and expression." If this is so, then the break between paragraphs, between scenes, and chapters serve as more than stop signs, a signal that something has ended, but more of an oasis, an invitation to the reader to respite, reflect, and ponder the meaning of what they have read.
Consider this pair of paragraphs from Let the Great World Spin by Colum McCann:
Laugh, Claire. Let it out.
A good doctor. He would not let her take pills. Try each day just to laugh a little bit, it's a good medicine, he said. Pills were a second option. I should have taken them. No. Better off to try laughing. Die laughing.
The use of white space is minimal, but the paragraphs break of like chiselled brick and hint at Claire's pain more deeply than the words themselves.
White space can be used to build suspense and tension in a story. It's use is tantamount to squeezing the hand of the person next to you in the movie theatre. A wordless summary that, yes, things are about to get worse, and a space for the reader to anticipate just how conditions will worsen.
Dialogue is one way to create white space, but, it's the paragraph that truly creates white space that readers can wade into, splash around, and stay awhile before moving on deeper into the prose. Spaces between paragraphs allow the reader, in a single glance, to have faith in the page they are about to read, or, conversely, when faced with a dense page of words, to put the book aside until a time when they can wade deep and long.
The page is the writer's stage which must be dressed, designed, and populated in visually diverse and interesting ways.
Writer challenge: Skim your work, page by page without reading the text. Are you using white space artfully? Is the page too filled with short, choppy paragraphs that allow for no deep swimming? Is there page after page of long, dense lines without many breaks?