How long was it before the universe became transparent?

The universe became transparent approximately 380,000 years after the Big Bang, during a period known as recombination. At this point, the temperature of the universe cooled enough for protons and electrons to combine and form neutral hydrogen atoms, allowing photons to travel freely. This event marked the release of the cosmic microwave background radiation, which provides a snapshot of the universe at that time. Prior to recombination, the universe was opaque due to the dense plasma of charged particles.