What are the rules of binomial nomenclature ? 

Explanation

Binomial nomenclature naming system was given by biologists all over the world.
This naming system using a two word format was found convenient.
Other universal rules of nomenclature are as follows:
(1) Biological names are generally in Latin an written in italics. They are Latinised or derived irrespective of their origin.
(2) The first word in a biological name represent the genus while the second component denotes the specific epithet.
(3) Both the words in a biological name, when handwritten are separately underlined or printed in italics to indicate their Latin origin.
(4) The first word denoting the genus starts with a capital letter while the specific epithet starts with a small letter.
 If can be illustrated with the example of Mangifera indica.
Name of the author appears after the specific epithet i.e., at the end of the biological name and is written in an abbreviated form eg. Mangifera Indica Linn.
It indicates that this species was first described by Linnaeus.