Question

what is an emulsion and how they are classify ?

Answer 1

Emulsion is a mixture of two or more liquids that are not immiscible.

Emulsions are formed from the component liquids either spontaneously or, more often, by mechanical means, such as agitation,. Unstable emulsions eventually separate into two LIQUID layers.

Therar are two types of emulsions.
first, an oil-in-water emulsion, wherein the oil is the dispersed phase, and water is the dispersion medium
. Second, they can form a water-in-oil emulsion, wherein water is the dispersed phase and oil is the external phase.
Multiple emulsions are also possible, including a "water-in-oil-in-water" emulsion and an "oil-in-water-in-oil" emulsion.

Examples: homogenised milk, brewed coffee, butter etc.,