Tech Tips You Should Know, But Don't

What people don’t know about basic computer tricks is pretty shocking, David Pogue found while gathering info for his New York Times column. After a call for tips from readers, all involved “soon discovered that what’s common knowledge isn’t the same as universal knowledge.” Here follow some of the choicest secrets, which Pogue urges us to “pass along to ... well, you know who they are.”

Don't, repeat don't, give out your personal information over email: You're being phished.
Also, nobody in Nigeria is actually going to give you $40 million.
On your cell phone, you can press "Send" to recall a recent contact. Rekeying the number is unnecessary.
Google really can do anything, from calculations to exchange rates.
If you think your hard drive is full, make sure you don't have 100 gigs in the recycle bin.