Understanding Latency: What Ping Actually Measures and Why It Matters

Ping measures the round-trip time for a packet to travel from your machine to a destination and back. That's the simple explanation. The nuanced explanation is what separates someone who can diagnose network issues from someone who just knows "my internet is slow." What happens during a ping The ping command sends an ICMP Echo Request packet to the target. The target's network stack receives it and sends back an ICMP Echo Reply. The time between sending and receiving is the round-trip time (RTT). ICMP operates at the network layer (Layer 3). It doesn't use TCP or UDP. This means ping results tell you about network-layer connectivity but say nothing about whether a specific application port is reachable or whether the TCP handshake will succeed. This distinction matters. A server can respond to ping while its web server is completely down. Conversely, many firewalls block ICMP, so a host can be fully functional but unreachable by ping. What the numbers mean A typical ping result shows f