Sybil Attack is an assault where one entity illegitimately assumes multiple identities. This is akin to a single person casting multiple votes in an election by pretending to be many different voters. In the digital realm, this can undermine the network's integrity by allowing an attacker to exert a disproportionate influence. A real-life example of a Sybil attack can be observed in the realm of social media platforms, where it's not uncommon to see entities creating multiple fake accounts to manipulate opinions or trends.