Hero Link is a code word used in the Hero Factory TV Show for the heroes to hold hands and stay together during an intense whirlwind or other such emergencies.
The Hero Link, as ordered by Stringer, was first and only mentioned in HF004 when Von Nebula used his black hole to take away the heroes' weapons. During such an emergency a hero only need to utter the phrase "Hero Link!" and immediately they know to hold hands. Though the origin of this code has yet to be revealed it is clear that every hero knows what to do when it is said. Not even Von Nebula's black hole could pull these robots away from their spot so long as their "Hero Link" remained active.