What "cam-to-cam" actually means
Cam-to-cam — sometimes written cam2cam — simply means both cameras are on. You are not watching someone; you are meeting them. Each side can see and hear the other, which changes the whole dynamic: the conversation becomes a two-way street with real eye contact, not a one-way stream with a chat box attached.
On SayHiCam cam-to-cam is always part of a 1-on-1 video chat — two people, no audience. If you want the jargon-free version of every term like this, the webcam chat page covers the browser side of things, and live video chat explains what "live" really means here (real time, not a broadcast).
Any device you already own
There is nothing to install. On desktop, open SayHiCam in your browser and allow camera and microphone access when prompted. On your phone it is the same story — the mobile browser handles the camera, and the layout adapts to a smaller screen. If your device can handle a video call, it can handle cam-to-cam.
A small tip that matters more than any feature list: face a window or a lamp, not away from it. Good light does more for a first impression than a perfect opening line.