Incoming requests are sent to servers in turn so one server does not receive them all.
<div class="demo"><div class="head"><b>LOAD BALANCER</b><span id="request">request #1</span></div><div class="scene"><div class="gateway">IN<br><strong>→</strong></div><div class="route">ROUTE<br><strong id="route">A</strong></div><div class="servers"><div class="server" id="a">SERVER A <b>0</b></div><div class="server" id="b">SERVER B <b>0</b></div><div class="server" id="c">SERVER C <b>0</b></div></div></div><div class="foot"><span>A → B → C → A</span><span>tap to route</span></div></div>.demo{width:min(94vw,690px);height:min(86vh,310px);padding:clamp(10px,2.4vmin,20px);border:1px solid var(--line);border-radius:14px;background:var(--surface);display:flex;flex-direction:column;gap:clamp(7px,2vmin,14px);font:600 clamp(9px,2.5vmin,15px)/1.3 ui-monospace,monospace}.head,.foot{display:flex;justify-content:space-between;gap:8px}.head b,.gateway strong,.route strong{color:var(--accent)}.head span,.foot{color:var(--muted)}.foot{font-size:.82em}.scene{flex:1;min-height:0;display:flex;align-items:center;justify-content:center;gap:clamp(5px,2vmin,20px)}.gateway,.route{border:1px solid var(--line);border-radius:8px;background:var(--bg);padding:.65em;text-align:center;min-width:19%}.gateway strong,.route strong{font-size:1.8em}.servers{width:42%;display:grid;gap:clamp(5px,1.4vmin,10px)}.server{border:1px solid var(--line);border-radius:6px;background:var(--bg);padding:.5em;display:flex;justify-content:space-between;opacity:.55;transition:opacity .2s,border-color .2s,background .2s}.server.on{opacity:1;border-color:var(--accent);background:color-mix(in srgb,var(--accent) 12%,var(--surface))}.server b{color:var(--accent)}const ids=['a','b','c'],counts=[0,0,0];let request=0;function route(){const index=request%3;counts[index]++;ids.forEach((id,i)=>{const el=document.getElementById(id);el.classList.toggle('on',i===index);el.querySelector('b').textContent=counts[i]});document.getElementById('route').textContent=ids[index].toUpperCase();document.getElementById('request').textContent='request #'+(request+1);request++}route();const timer=setInterval(route,700);document.querySelector('.demo').addEventListener('pointerdown',()=>{clearInterval(timer);route()})Round robin sends each request to the next server in a list and wraps around after the last. It is simple and spreads traffic evenly when server capacity and request cost are similar.
The demo routes numbered requests around three servers and counts their work. Real deployments also need health checks to exclude failed servers, and may need weights or another policy when capacities differ.
Consider it as a starting policy for distributing requests among equivalent servers.