Mesh (full-mesh, peer-to-peer) is the simplest WebRTC conferencing topology: every participant sends their media directly to every other participant, with no media server in between. For two to a few people it is ideal — lowest possible latency, no server cost, and naturally encrypted end to end. The problem is that it doesn't scale: each participant must encode and upload a separate copy of their stream to everyone else, so upload bandwidth and CPU grow with the number of participants and become impractical past roughly four people. Beyond that, conferences move to an SFU, which lets each client upload just once. Mesh remains the right choice for one-to-one calls and tiny groups.
