"When I click on a certain category of e-mails in Gmail I get nine visible entries. I can delete them one at a time but I would like to delete them all at once. How can this be done?"

When you say "a certain category of e-mails," Bill, I'm assuming you mean a label. But whatever the case, there are plenty of situations when it would be helpful to select a visible batch of messages, then apply a function (like delete) to them. The process for doing so is hiding in plain sight.

1. Open Gmail in your browser.

2. Click a label, apply a filter, or do whatever you like so that only the messages you want are visible.

3. Near the top of the screen, just below the search field, you'lll see a square box inside a rectangular box. That's the Select tool, and if you click that square, it'll select all visible emails.