Simplify the following text for a Grade 8 native English-speaking person.
Original: The Human Rights Campaign ( HRC ) is the United States ' largest LGBT advocacy group and claims more than 750,000 members and supporters .
Simplified: They are the largest such group in the United States , with over 750,000 members and people who support them . The HRC works to ensure that the rights of these individuals are protected and respected throughout the United States .