C Linnaeus, the father of taxonomy, introduced the binomial system of nomenclature. He dealt about this in the 10th edition of his book 'Systema Naturae' which was published in 1785.
This is a system of providing organisms with distinct scientific names which consist of two words, the first one indicating a generic name (Genus). The first and second together form a specific name (Species). These two words are in Latin or Latinized if derived from other languages.
Genus is a common noun and starts with a capital letter. It indicates the name of a group. In the specific name, the second word is like an adjective and begins with a small letter excepting the cases when it denotes proper nouns like the name of a person, place or the like. It may then, start with a capital letter.
The names when written should be underlined to indicate their Latin origin. In the printed form, they should be italicized.
The name of the author who has first described the plant in scientific journals may be appended in full or abbreviated form. For example - the botanical name of mango is Mangifera indica Linn. All three comprise binomial nomenclature.
The generic name is one for all species whereas the species name is variable. For example - Ficus bengalensis, Ficus religiosa, Ficus glomerata, which represent banyan, peepul and fig trees respectively. All have one generic name Ficus but their species names are F.bengalensis, F.religiosa, F.glomerata.