Brandjacking refers to acquiring the online identity of a brand through means like impersonation, cybersquatting, or phishing in order to benefit from the brand's goodwill. It can be done for free publicity or to damage a brand's reputation. The document discusses examples like a Twitter account parodying BP's response to an oil spill that gained more followers than BP's official account. It recommends notifying customers of issues immediately, reporting phishing sites, putting out press releases, and having proper internal communication to address brandjacking incidents.