Interstellar cloud

An interstellar cloud is a denser-than-average part of the interstellar medium, (ISM). It is matter and radiation in the space between the star systems in a galaxy. 

An interstellar cloud is formed by the gas and dust particles from a red giant in its later life.

The cloud is made of gas, plasma, and dust in our and other galaxies. 

Its hydrogen can be:
neutral, making it an H I region; 
ionized, or plasma making it an H II region; or 
molecular (molecular clouds). 

Neutral and ionized clouds are sometimes also called diffuse clouds. 

 Sources 

Category:Nebulae
Category:Hydrogen
Category:Red giants