Define "sybil attack" in blockchain environments.

A "sybil attack" in blockchain environments refers to a situation where a single malicious actor creates multiple fake identities (or nodes) to manipulate and gain disproportionate influence over the network. By flooding the network with these identities, the attacker can control a significant amount of the network's activities, making decisions that may benefit them at the expense of legitimate participants. This undermines the trust and integrity of the network since the attacker can outvote or overpower genuine users, thereby disrupting normal operations and potentially leading to harmful actions such as double-spending or altering the consensus process.

The concept of sybil attacks is particularly relevant in decentralized environments, where trust relies heavily on an accurate representation of user identities. Understanding how sybil attacks function is crucial for developers and network administrators as they design systems to mitigate these vulnerabilities. Implementing mechanisms such as proof of work, proof of stake, or other identity verification processes can help reduce the risks associated with sybil attacks.