From the Hollaback! website:
Hollaback! is a global, people-powered movement to end harassment — in all its forms. We believe that we all deserve to be who we are, wherever we are.
We believe we all have a role to play in disrupting harassment and building a culture where it is no longer seen as “just the price you have to pay” for being a woman, LGBTQ+, a person of color, or any other marginalized identity. We teach people to take action, and to reach across their own identities to ally with others and establish a united front against harassment each time we witness it.