If you have satellite Internet, you know you have so many megabytes of data each month. If you go over, your account is "throttled" until you purchase more.
A little over a month ago I was going along with more than half of my data unused, and it was only 4 days until it reset.
That's why I was shocked the next day when the Internet quit working. I checked and sure enough, it was throttled. Something had used more than 6 megs of data in a day. It had even used some of the "bonus" data (2 a.m. to 6 a.m. or something like that).
I'd been leaving the computer turned on at night - big mistake!
In the weeks since then, I've figured out what happened. No one is sneaking through the woods with a laptop to steal my WiFi. No one is parking in my driveway, either. I already knew that; the dogs would have had fit.
No - the data drain comes from "Pop unders." And they aren't just static pages. They have video running - which eats up data at an alarming rate.
It usually happens to me if I've visited news sites. And the worst of it is, after you close that page, the pop under is still there, hiding behind whatever else you have open (such as Active Rain, your own website, etc.) Fortunately for me, one of those sites had sound as well as movement, and that alerted me to go exploring.
It just happened again today. I closed a page and there lurking behind were TWO of those unwanted visitors! They'd used up a whole meg of data - but that was OK, because I still had plenty and the system resets at midnight tonight.
Live and learn - and I've learned to check for intruders every time I've visited a news site - or any site that has a ton of ads.