What is a name? Way back when, people were given a first name and the last name was typically noted as the son or daugther of the father. For example, John nee Harris, Mary nee Harris, Bertha Marie Pedersdautter or Neils Pederson. All these names have a word that indicate they are the son/daughter of Harris or Peder. The customs of surnames is variable depending upon your heritage; for example, the hispanic culture has in the past included the father and mother's surname in the child's last name.
We have all been given surnames (last names). Have you ever thought about what/where your last name came from? Surnames could reflect a person's occupation, locality, or origin. You probably are asking, so what is the big deal? We all have last names. How is understanding my surname (last name) going to be of any assistance in researching my family history? The answer is knowing and understanding your surname (last name) can give you clues into where your family may have lived and their occupations. Additionally, you can possibly discover new relatives.
One mistake almost every new genealogist makes, is to assume that the way your last name is presently spelled is the only correct spelling. So for example, if your last name was Harris, the spelling of Haris, Harries, Harris, or any other name, could not be related to you. It is possible the person with the different spelling is not related, but don't write them off to quickly, as they could be related to you and they just spelled their last name differently. Family Search has a brief and to the point article about the spelling of surnames here.
I came across a website titled Forebears. This site provide a search engine for names where you can type in the surname, see a meaning behind the name, origin and distribution map for the name, and possible alternate spellings of the name. If you would like to research the meaning of a surname, click Forebears Surname. Have fun!