Here's a breakdown:

* Spectral Class: This is determined by analyzing the star's light spectrum. Different elements absorb and emit light at specific wavelengths, creating unique patterns in the spectrum. These patterns correspond to a star's surface temperature. The main spectral classes are:

* O: Hottest, blue-white

* B: Hot, blue-white

* A: Hot, white

* F: Moderately hot, yellow-white

* G: Sun-like, yellow

* K: Cooler, orange

* M: Coolest, red

* Magnitude: This describes a star's apparent brightness as seen from Earth. It's a logarithmic scale, with lower magnitudes indicating brighter stars. There are two types of magnitude:

* Apparent magnitude: How bright a star appears from Earth.

* Absolute magnitude: How bright a star would appear if it were at a standard distance of 10 parsecs (32.6 light-years).

Together, spectral class and magnitude provide valuable information about a star's properties, including its temperature, luminosity, and even its age.