A:AnswerAll monitors have one or more of the following connectors...
Sub-D - aka VGA or DE15 connector
DVI (-D) is the most common variant.
HDMI - starting to show up in the budget priced [under] $150 monitors and will soon be the de facto standard. -- Much the same way VGA has been the de facto standard for so many years.
If there's a monitor [that's under 30"] out there that can accept a USB connection, it's news to me.