In “Tech Tips for the Basic Computer User,” David Pogue points out the difference between common knowledge and universal knowledge. (The piece, which includes a list of seemingly obvious tips, was the most emailed article at the NY Times site for a few days.)

One of these days, I’m going to write a book called, ‘The Basics.’ It’s going to be a compendium of the essential tech bits that you just assume everyone knows — but you’re wrong.

(I’ll never forget watching a book editor at a publishing house painstakingly drag across a word in a word processor to select it. After 10 minutes of this, I couldn’t stand it. ‘Why don’t you just double-click the word?’ She had no clue you could do that!)”

Many readers chimed in with other “basics” that they assumed every computer user knew — but soon discovered that what’s common knowledge isn’t the same as universal knowledge.

It’s easy for those of us immersed in the tech world to forget what it’s like for normal folks to use a computer. For example, it’s tempting to think “we should just do this in Twitter” while forgetting that most normal people have no clue what Twitter is (...or 37signals for that matter).

And if you’re only trying to reach a tech savvy audience, it’s fine to write these folks off. But the bigger an audience you want to reach, the more you need to remind yourself that a large part of your target group is missing knowledge that you think is obvious.