Silica gel is a highly porous and adsorptive material made from sodium silicate through chemical reactions with acids, followed by aging and drying processes. It is primarily composed of silicon dioxide (SiO₂) and is chemically stable, non-toxic, and odorless. Due to its abundant microporous structure, silica gel exhibits excellent adsorption properties and is widely used as a desiccant, catalyst carrier, and purifier.

Silica gel typically appears as transparent or translucent granules, spheres, or blocks. Depending on its application and production process, it can be categorized into various types, such as regular silica gel, fine-pore silica gel, macro-pore silica gel, and silica gel adsorbents. Each type differs in adsorption capacity, particle size distribution, and mechanical strength to suit specific needs.