when were surnames introduced to europe?

Answer 1

In the British Isles, hereditary surnames were adopted in the 13th and 14th centuries, initially by the aristocracy but, eventually, by everyone. By 1400, most English people and Scottish people had acquired surnames, but many Irish people, Highland Scots and Welsh people did not adopt surnames until the 17th century, or later.

On the Continent, surnames became officially introduced with the "Code Napoleon", starting in France and the French territories in 1804.

Before that, most people had nicknames (one of my forefathers was called "Zwarte Hein" ("Black Hein") because of his very dark skin, my paternal grandfather was called "De Witte van Nand" ("The Greyhaired son of Ferdinand"), others had patronyms or matronyms (If I had lived 50 years earlier, I would have been called "Louis van Frans van de Witte van Nand), others were named after the place the were born (De Witte van Nand was also known as "Louis Van Thienen van de Rode Heide"), or their profession. As you can see, several had more then one name. Some of these "informal" names lived on until the early 60s in Belgian villages.

Answer 2

Code Napoleon was introduced in 1803. One of the laws was that people need to have a surname by law. Until the 19th century it was not a necessity. All over Europe this code was enforced, so most people either added or changed their surnames.
http://www.history-magazine.com/codenap.html
http://www.napoleonguide.com/codenap.htm

Answer 3

Middle Ages