In the world of stars - class-VII

Stars are sequence can range from a tenth of the mass of the sun to up to $200$ times as massive.

The phrase star stuff refers to the fact that the heavy elements (like carbon, oxygen, and iron) that make up our bodies and the Earth were synthesized through nuclear fusion in the cores of stars and later dispersed into space.

Apparent magnitude measures the brightness of a star as observed from Earth. Absolute magnitude measures intrinsic luminosity at a standard distance, while light year is a unit of distance.

A star is a luminous globe of gas producing its own heat and light by nuclear reactions (nuclear fusion). They are born from the nebula and consist mostly of hydrogen and helium gas. Surface temperatures range from 2000 C to above 30,000 C, and the corresponding colors from red to blue-white. 

Nebulae are the collection of massive clouds of dust, hydrogen and helium gas, and plasma. These form the origin of the birth of a star.

Main sequence stars fuse hydrogen atoms to form helium atoms in their cores. About 90 percent of the stars in the universe, including the sun, are main sequence stars. 

Main sequence stars are in the longest stage of their life cycle, where they fuse hydrogen into helium in their cores. This process releases the energy that makes them shine steadily.

A star is a massive, luminous sphere of plasma held together by its own gravity. The intense pressure and heat at the core are necessary to sustain nuclear fusion.

Smaller elements fuse together to form massive elements. this process is known as nuclear fusion

All main sequence stars (including the Sun) are in hydrostatic equilibrium. That is, the inward force of gravity, which tends to compress the star, is balanced by the outward force due to the pressure.

Stars form within giant molecular clouds, which are composed primarily of hydrogen gas. Gravity causes these clouds to collapse, eventually leading to the formation of protostars.

An object is considered a protostar for as long as material is still falling inward. For our Sun, and stars of the same mass, the protostar phase would have ended after approximately 100,000 years. After this, the protostar stops growing and the disk of material surrounding it is destroyed by radiation.

If the protostar was unsuccessful in acquiring enough mass, a brown dwarf will come into shape. These substellar objects that are unable to sustain hydrogen fusion reactions in their cores, due to their insufficient mass

A protostar is an early stage in stellar evolution where a cloud of gas and dust is collapsing under gravity. It is often associated with a glowing, dense, and relatively cool appearance before reaching the main sequence.

Since the forces balance, it forms a stable main sequence star

A star's composition is mostly made of gases of which hydrogen and helium forms the most largest component of it. Hydrogen being the lightest element will get fused to helium

As a protostar contracts, it heats up and begins to radiate energy. Because the surface temperature is relatively low compared to mature stars, the radiation is primarily in the infrared or long-wavelength red spectrum.

Range of star masses for high-mass stars varies from about $8$ to $200$ solar masses.