13 categories, each one filed by what the camera looks at.
Categories describe what a camera is pointed at, not who runs it. A camera can carry more than one label, so a harbour cam that also watches the ferry berth shows up under both Beach and Ports. Traffic is by far the largest group because road agencies publish their whole network as open data; a category with only a handful of cams usually means few have been tagged that way yet, not that the view is rare.
If you already know where you want to look, starting from the country pages and narrowing there beats scrolling a global category list, and a country page shows its own biggest categories at the top. Expect a mix of formats inside any category: some cameras send video, others publish a still image they overwrite every few seconds.