While writing some documentation, I again thought about the need for preciseness of words. A writer needs to use quite a different vocabulary than a speaker. For instance when speaking, one could say 'You have to turn it on first.' But when writing it's more clear to say 'First, one must turn the T.V.'s power on.'
The written word has no context, and no chance to correct it's meaning when the reader is confused.
Also note my frequent use of 'one' to instead of 'you'. I don't mean 'less than two', but I also don't mean 'you personally'. Using 'one' is a more formal choice, but I think it classes the joint up a tad.
If you're still interested in this train of thought, peep these succint and informative articles from Wikipedia. They can apply to much more than just Wikipedia.