|What is a webcam?|
A (usually) low-medium resolution camera that is connected directly to the pc/laptop and relies on the computer for power/processing - it cannot be used as a standalone camera.
Do webcams hook to a computer w/out additional software? They need a computer to be able to work and they come supplied with their own software.
Can a webcam somehow take a still photo? Yes
(Maybe a website allows or arranges this?) No, you can do it yourself with the supplied software.
Can THAT still photo be posted to a webpage? Yes.
"I've always been mad, I know I've been mad, like the most of us..." Pink Floyd