Latency
Latency is the round-trip time for a data packet to travel from your device to a server and back, usually shown in milliseconds (ms) on speed tests as “ping”.
Why it matters
Low latency feels instant; high latency feels laggy. Streaming video can buffer through delay; video calls, gaming, and VoIP suffer when latency is high because turns and audio arrive late.
Example in UK broadband
Two households might show the same download speed on a speed test, but one has 15 ms ping and another 60 ms to the same test server—the second may feel worse for competitive gaming or patchy on video calls. Full fibre and a calm Wi‑Fi path usually help; distance to the test server also changes the reading.
Related terms
Read more
Why latency matters more than Mbps for gaming and calls. You can also run a focused check at Laggy.uk.