What critical data do eclipsing binary systems yield beyond the orbital period?

The stars' radii and highly accurate individual masses

Eclipsing binaries are considered perhaps the most informative type of binary system because they are oriented nearly edge-on relative to the observer's line of sight, causing one star to periodically pass in front of the other. The specific characteristics of these transits—namely the duration and the depth of the light blockage—provide exceptionally rich data. The duration analysis is crucial for deriving the orbital period, but the depth of the eclipse, which depends on the relative sizes of the stars as they obscure each other, directly yields information about the physical radii of the components. When this dimensional data is successfully combined with radial velocity measurements obtained through the Doppler shift observed in their spectra, astronomers can achieve highly accurate determinations of the individual masses ($M_1$ and $M_2$) for both stars in the system, resulting in the highest precision estimates available.