What is the orbital filling order for an atom?

The orbital filling order for an atom follows the Aufbau principle, which states that electrons fill orbitals starting from the lowest energy level to the highest. The order is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, and 7p.