All cell culture media have a basis of a synthetic mixture of inorganic salts known as the physiological or balanced salt solution (BSS). All the physiological salt solutions are derived from the salt solution originally described by Sydney Ringer (1885). The first balanced salt solution developed specifically for supporting the metabolism of mammalian cells was Tyrode's solution. Since then, many modifications have been done to obtain better buffering salt solutions and to prevent calcium precipitation.

The function of a salt solution is:

• To maintain the medium within the physiological pH range.
• To maintain intracellular and extracellular osmotic balance.

Hanks' Balanced Salt Solution may be modified by adding glucose to serve as an energy source. It is most commonly used together with trypsin solution for tissue disaggregation and monolayer dispersal since the presence of calcium and magnesium ions may hinder the trypsin activity. It is also used for routine immunohistochemical testing and as a general-purpose solution for washing cells in various haematological and molecular biology procedures.