What does the term "latency" refer to in communications?

The term "latency" specifically refers to the delay incurred in data transmission before the actual transfer of data begins. This delay can happen for various reasons, such as the processing time required by network devices, the distance data has to travel, and any congestion within the network. Understanding latency is crucial because it affects the performance of network applications, particularly those requiring real-time communication, such as video conferencing or online gaming, where a high latency can lead to noticeable delays in communication.

In contrast, the other choices focus on different aspects of data transmission. The amount of data transferred at once pertains to bandwidth, not latency. The speed of data transmission is often linked to transmission rates, measured in bits per second, which differs from the concept of latency. Reliability of data transfer involves error rates and the ability to consistently deliver data without loss, which is not related to the delay in transmission that latency describes.