How did Niels Bohr explain spectral lines?

Niels Bohr explained spectral lines through his model of the atom, which proposed that electrons occupy specific energy levels or orbits around the nucleus. When an electron transitions between these levels, it either absorbs or emits a photon with energy equal to the difference between the two levels, resulting in distinct spectral lines. This quantization of energy levels accounts for the discrete wavelengths observed in atomic spectra, providing a clear explanation for the patterns of lines seen in emission and absorption spectra. Bohr's model successfully explained the hydrogen spectrum and laid the groundwork for modern quantum mechanics.