Connect appliances with an HMDI switch

I've always marvelled at people who are such experts with electronic or electrical gadgets. With tons of such gadgets around, it's really a wonder how one knows what is what and what plugs into which. Take for instance the HDMI Switch. All I know about it, is that it serves something like a switcboard where multiple HDMI appliances can be connected. And I think this auto switch provides LED display, IR remote control and push button for port selection.