I noticed in a lot of books that once in a while the words in a sentence will have extra spacing. Is that some kind of style which is supposed to have an effect on how the reader reads the sentence or some kind of typing error? Do you know what I mean? I feel kind of silly asking this question... If it's some kind of style, what's the effect it's supposed to have?
Most likely is justified text, meaning the line is adjusted to line up on both the left and right marginsm except the final line of each paragraph. This is done by addin space between letters, spread evenly across each line. Many people find this distracting, so most books left-align the text instead ("ragged right"). However, newspapers and magazines, with several columns per page, often use justified text so the overall page appearance looks neater.
My eyes! I see it on my monitor even though it doesn't exist! Argh! Its like that you are now blinking manually, breathing manually and the ever more evil 'Good news everyone! You are now reading this in my voice!' Or the you read this first, and this last, kind of thing. It is very distracting for me! People who use it go on my naughty list, like Stephen King.
Cogito already answered it, right? Sometimes a double space is not intentional, but is an actual mistake: Can not use example here, forum removes the extra space automatically. Font issues can also make it look like two spaces exist because of bad kerning, but that is a different topic altogether.
