What is the Catholic understanding of the idea that Jesus descended into Hell?

The Christian understanding that everyone was born with origin sin, and then when Jesus/God was killed at the cross, and then he was resurrected from death after 3 days. From what I understand, there is the idea of Jesus descending into Hell to free the spirits/souls of people. Who were these people? Was it everyone before his time that died? Did it include the righteous and wicked people or prophets also? Is this a creed based on belief only or is there scripture to back this up somewhere?