Short answer
Low latency means traffic goes back and forth quickly, even if bandwidth is not extremely high.
Ping in practice
Ping is often measured in milliseconds. Lower is better for games, video calls and remote control where response is noticed immediately.
Latency is not the same as speed
You can have high download speed but poor responsiveness if latency is high or varies a lot.
Common causes of high latency
WiFi interference, overloaded routers, long distances, VPN routes and saturated uploads can increase latency.
Common questions
Is 20 ms ping good?
Yes, 20 ms is normally good for most real-time needs.
Can VPN increase latency?
Yes, traffic goes through the VPN server and may take a longer route.