Quick Definition
Woot ("Root!") is an exclamation referring to the seizure of root (administrator) access on a system targeted for attack.
In recent years, the exclamation has been seized upon across the broader culture as an expression of happiness or joy, reflecting the attacker-centric perspective of its original usage in network chats amongst hackers, where it was used to notify collaborators of successful penetration at the moment when administrative privileges were achieved.