Perlite is a naturally occurring volcanic rock. When furnaced at high temperatures, Perlite “pops” and expands up to 15 times its original volume. (Gotta have my corn pops.) The resulting lightweight particles are made up of microscopic spheres with a porous, broken surface that promotes plant growth. This allows aeration and drainage of the root system and provides holding capacity for water and nutrients.

Perlite is the white one. If you are looking for the tan one, you are probably looking for vermiculite. 

You should use perlite with succulents, not vermiculite. 

Works great with orchids!

What is perlite used for?

• Used to improve drainage and aeration in potting mixes
• Help prevent soil compaction to improve growing conditions
• Organic and registered with the Organic Materials Review Institute (OMRI) for earth-friendly gardening
• Weed-free soil amendment improves soil without adding unwanted ingredients

Perlite trivia: 

• Perlite is a natural resource that is commonly mined in Greece, Turkey, USA and Armenia
• In addition to its horticultural usages, Perlite is also used extensively in construction. 
  
• Perlite makes an amazing filter medium. Many breweries use perlite to filter their beer.