Packet loss can adversely affect the quality of applications, particularly those requiring real-time data transfer, like video conferencing or online gaming. 

• Causes of Packet Loss: Packet loss can occur due to various reasons including network congestion, faulty routers or other networking hardware, poor quality cables, or software bugs. In wireless networks, interference and signal strength issues can also lead to packet loss.

• Impact on Network Performance: Packet loss can significantly degrade network performance and user experience. In VoIP (Voice over Internet Protocol) calls, it can cause audio glitches or dropped calls. In video streaming, it can lead to poor video quality or buffering issues.

• TCP vs. UDP: The impact of packet loss varies depending on the protocols used. TCP (Transmission Control Protocol) has mechanisms to detect and retransmit lost packets, which can introduce latency. UDP (User Datagram Protocol) does not retransmit lost packets, which is preferable for real-time applications but can result in data loss.

• Latency and Jitter: Along with latency (delay) and jitter (variance in delay), packet loss is a key metric for assessing the quality of a network connection, particularly for interactive applications.

• Redundancy: In some critical applications, redundancy techniques such as sending duplicate packets or using error correction codes can help mitigate the impact of packet loss.

Managing packet loss is essential for maintaining efficient and reliable network communication, especially in scenarios where timely and accurate delivery of data is critical.