Last week, I wrote an entry on my blog that began like this:

“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.

* You can double-click a word to highlight it in any document, e-mail or Web page.

* You can hide all windows, revealing only what’s on the computer desktop, with one keystroke: hit the Windows key and “D” simultaneously in Windows, or press F11 on Macs (on recent Mac laptops, Command+F3; Command is the key with the cloverleaf logo). That’s great when you want examine or delete something you’ve just downloaded to the desktop, for example. Press the keystroke again to return to what you were doing.

* You can enlarge the text on any Web page. In Windows, press Ctrl and the plus or minus keys (for bigger or smaller fonts); on the Mac, it’s the Command key and plus or minus.

* The number of megapixels does not determine a camera’s picture quality; that’s a marketing myth. The sensor size is far more important. (Use Google to find it. For example, search for “sensor size Nikon D90.”)

* You can tap the Space bar to scroll down on a Web page one screenful. Add the Shift key to scroll back up.

* You can use Google to do math for you. Just type the equation, like 23*7+15/3=, and hit Enter.

* Google is also a units-of-measurement and currency converter. Type “teaspoons in 1.3 gallons,” for example, or “euros in 17 dollars.” Click Search to see the answer.

* You can switch from one open program to the next by pressing Alt+Tab (Windows) or Command-Tab (Mac).

* Just putting something into the Trash or the Recycle Bin doesn’t actually delete it. You then have to *empty* the Trash or Recycle Bin. (Once a year, I hear about somebody whose hard drive is full, despite having practically no files. It’s because over the years, they’ve put 79 gigabytes’ worth of stuff in the Recycle Bin and never emptied it.)

What are your favorite basics-that-you-thought-everyone-knew? Let us know in the comments for this column at nytimes.com/pogue!