In simpler terms, it's the delay between a user action and the response from the network to that action. 

• Measurement of Time Delay: Latency is typically measured in milliseconds (ms) and represents the round-trip time it takes for data to travel from the sender to the receiver and back.

• Impact on Network Performance: High latency can significantly impact the performance of a network, particularly in applications that require real-time interaction, such as online gaming, video conferencing, and VoIP (Voice over Internet Protocol).

• Latency vs Bandwidth: While often confused with bandwidth (the amount of data that can be transmitted over a network in a given amount of time), latency is specifically about the delay in transmission, not the speed of data transfer.

• Low Latency in Certain Applications: Low latency is crucial in certain applications. For instance, financial trading systems require extremely low latency to execute trades quickly. Similarly, low latency is vital in telemedicine and remote surgery applications.

• 5G and Latency: One of the key improvements with 5G technology in mobile networking is significantly reduced latency, which is vital for technologies such as autonomous vehicles and augmented reality (AR).

Understanding and managing latency is critical in network and application design to ensure that users have a smooth and efficient experience, especially in real-time and interactive applications.