Software Defined Radio
An SDR radio is a software defined radio. That means a radio receiver is connected to and controlled by a computer. A web based SDR Radio is one which you access and operate via the internet using your web browser. You do not need any other hardware. I have accessed these using Firefox and Microsoft Edge.
Web SDR's are usually decent Radios with a decent Antenna. If you connect to one you can listen to the radio through your earphones / speakers as if you were at the same location with a good Radio.
Using one of these gives you a taste of what can be picked up at a particular location, and there are many worldwide. Some have a set number of bands, others have a wider range. One I listen to regularly is at the University of Twente in the Netherlands. It has a wide range of Coverage.
An excellent one at Jodrell Bank in Cheshire covers 2M, 70CM, 6M, 80M and 60M as well as PMR and CB. These are worth having a play with, you can't break them. If you mess up the settings, just close the web page and start again.