Telephone, cable, plumbing, or air conditioning repair people show up to do work when no one called them. Service or delivery trucks are often parked nearby with nobody in them. Furniture has been moved slightly, and no one knows why. A bug is a hidden listening device, or a hidden video camera, used to spy on people and gather intelligence on their activities and conversations. Microphone or a baby monitor.
Bugs can also be complex listening device like the infinity transmitter.
There are hundreds of websites offering to Fed-X you the bug of your chioce. It is estimated that there were 100,000 bugs or listening devices sold in the United States during 1999. There are a lot of bugs and listening devices out there and in use today. Remember, corporate America accounts for only 25,000 bugs sold in 1999. Most bugs in use today are used on the domestic front.