RTMP: To deliver an RTMP stream across the internet, you’ll need to start with an RTMP-compatible camera or encoder. You may be using an IP camera, software encoder, or hardware encoder.
HLS stands for HTTP Live Streaming. In short, HLS is a media streaming protocol for delivering visual and audio media to viewers over the internet.
RTSP: Real-time streaming protocol, or RTSP for short, is a protocol that helps manage and control live stream content rather than actually transmitting the content. It is considered a “presentation layer protocol.”