Two spaces, and commas

[geoff-h -at- MTL -dot- FERIC -dot- CA]

 Two spaces after periods are useful in text, particularly
 online text, that uses a monospaced (nonproportional) font:
 the extra space emphasizes the break between sentences.
 This sends a clearer signal to the reader's brain: "you've
 finished this sentence, and can start figuring out what it
 means before going on to the next one." With proportional
 fonts, the typography is such that the extra space
 generally becomes redundant. [No research to back me up
 here, but it fits with my observations and those of
 colleagues. Anecdotal evidence!]

 The "comma before the and" is one of those things that
 changes with editorial fads. A few years back, some writers
 and editors advocated a style known as "open punctuation",
 based on the idea that you should reduce punctuation to the
 minimum necessary to avoid confusion. I was brought up on
 this tradition, and I still often fall into the habit
 without thinking about it. However, after spending a few
 years editing for a living, I grew convinced that open
 punctuation is unreliable as a rigid rule. Yes, we should
 minimize structures that depend on convoluted punctuation,
 but making the items in a list distinct doesn't fall into
 this category. You'll never confuse someone by using the
 serial comma, and you will occasionally confuse someone by
 omitting it. The conservative approach is to stick with the
 comma.

 --Geoff Hart     @8^{)}     geoff-h -at- mtl -dot- feric -dot- ca
 Disclaimer: Speaking for myself, not FERIC.