I needed to buy a new Mac recently. I couldn’t bring myself to buy a legacy Intel Mac, but the new M1 Macs only support up to two displays. For the MacBook Air, MacBook Pro, and iMac that means you can connect one additional display along with the built-in display. For the Mac Mini, you can add two displays. I wanted a MacBook Air and already had two external displays which I wanted to keep using.
What are your options if you want to run more than two displays? Enter DisplayLink. DisplayLink (not to be confused with DisplayPort) is the name of a technology created by a company also named DisplayLink. It lets you send a video signal to a display over USB or Wi-Fi instead of via DisplayPort or HDMI. DisplayLink technology was first used in laptop docking stations but can now be found in other video related products including adapter cables and monitors.
DisplayLink has two components - a software driver installed on your computer and a hardware chip in the dock or adapter. The software driver presents itself as a one or more displays to the computer. The computer sends pixel data to the software driver, which then compresses the data and sends it over USB. The DisplayLink chip decompresses the data and sends the display signal to the (real) display.