I am often asked why it is considered a big deal by some for a writer to have at least a basic grasp of grammar and spelling; after all, that's why we have editors, right?
Well, I liken writers to fashion designers. Imagine a fashion designer who creates the best, most flattering jeans ever known to man. Now imagine this pair of jeans has a new type of zipper and a new type of button, and nobody has ever seen or used these before. Try as they might, customers find it impossible to figure out how to put on these jeans. In this case, does it matter that they're the best-fitting jeans ever created? Or are the (seemingly) little things getting in the way of the person's enjoyment of functional usage of the garment?
The point here is that it is extremely important to know your craft as a writer; people will respect you more for it, and they will have a better understanding of your work - which is the important thing.
That said, I'd like to review some commonly misused words and their proper usage.
Lay: To set something down
Lie: To be in a recumbent position
The difference is subtle, but basically I can lie down in surrender after I lay my weapons down.
less: reduction in comparison to something else - non-quantitative
fewer: reduction in comparison to something else - quantitative
So, in the Burger King ad I saw recently, it should promote their new "Satisfries" as having LESS fat (a non-quantitative measurement) and FEWER calories (can be counted) than regular fries. Now, if they had listed the grams of fat, that is quantitative, so they could say fewer grams of fat; similarly, if the fries were advertised with "caloric content" in mind, the ad could have read "less caloric content". As the ad ran, "less fat, less calories" it's just plain wrong.