What Is Latency?
Latency — the time a packet takes to travel from source to destination, measured in milliseconds (ms). Low latency means a responsive network.
How it works
Latency accumulates from distance (propagation), device processing, queuing under congestion and serialisation. Ping measures round-trip time — a packet's journey there and back. Gaming and voice calls suffer above ~100–150 ms; bulk downloads barely care.
Why it matters
Interviews love the bandwidth-vs-latency distinction: bandwidth is capacity, latency is delay. A satellite link can have high bandwidth and terrible latency. Troubleshooting slowness starts by measuring both — ping for latency, transfer tests for throughput.
Frequently asked questions
What is a good latency?
Under ~30 ms feels instant; under 100 ms is fine for most uses; voice/gaming degrade noticeably beyond ~150 ms.
What causes high latency?
Distance, congested queues, overloaded devices, and slow processing hops along the path.
How do I measure latency?
With ping — it reports the round-trip time to a destination in milliseconds.
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