Wikipedia
Bufferbloat is a phenomenon in packet-switched networks, in which excess buffering of packets causes high latency and packet delay variation (also known as jitter), as well as reducing the overall network throughput. When a router or switch is configured to use excessively large buffers, even very high-speed networks can become practically unusable for many interactive applications like Voice over IP (VoIP), online gaming, and even web surfing.
The bufferbloat phenomenon was initially described as far back as in 1985, and gradually became more recognized as an issue. It gained more widespread attention starting in 2009.
Some communications equipment manufactures placed overly large buffers in some of their network products. In such equipment, bufferbloat occurs when a network link becomes congested, causing packets to become queued in buffers for too long. In a first-in first-out queuing system, overly large buffers result in longer queues and higher latency, but do not improve network throughput and may even reduce goodput to zero in extreme cases.