In English (and many other languages) a last name , also called a 'surname' or a 'family name' is the name that all members of the family use as identity with that family.
Most last names are traditionally the last name of the father, his father before him, etc.
A last name is the name by which someone might address you as Mr. (name).
A first name is the individual name you were given to identify you apart from the other members of your family.
A first name is the name by which your family and friends address you.
When filling out documents, use the name given on your birth certificate (or other document), not a nickname used by friends or family.
Middle names are any additional name you were given at birth.
Not everyone was given a middle name at birth.
Some people have several middle names.
A middle name helps to differentiate your name from others who have the same first and last name.
The thing to remember when filling out such a form, whichever name you decide is your 'last name', it will be used to address you as Mr. (name), That name is the one that will be used to alphabetize you or your records in a data system.