What is a tap?
Taps are a hardware device which is installed “inline” on a piece of fiber optics or copper ethernet cable. Once installed, all data communications will arrive at its original destination AND also on a tools port.
Photos and additional information about those sold by my employer, can be found at:
Glossary
“inline“
For this example, lets assume we want to tap your personal laptop. For sake of discussion and simplicity lets also assume that laptop doesn’t have WI-FI. Your laptop is connected via a wire to your home internet router.
We would disconnect your laptop, plug it into the tap, and then connect a second cable to your home router. At this point the tap is inline.