latency
also: response time, delay
The time delay between when a request is made and when a response is received or an action completes. Lower latency indicates faster responsiveness.
Latency measures the time interval between initiating an operation and observing its result. In Linux systems, latency can occur at multiple levels: network latency (delay in packet transmission), disk I/O latency (time to read/write data), and application latency (time for software to process a request).
For example, network latency between your computer and a web server might be 50 milliseconds, meaning a ping request takes 50ms to reach the server and return. Similarly, disk latency measures how long it takes for a storage device to locate and retrieve data after a read command is issued.
Latency differs from bandwidth: bandwidth is how much data you can transfer, while latency is how quickly that transfer begins. A high-speed connection with high latency (slow responsiveness) can feel sluggish, while lower latency provides snappier interaction, which is critical for gaming, real-time systems, and interactive applications.