What is the Queen’s last name?

Question sent via email:

I’ve been wondering for along time and just out of curiosity, I wanted to know what the Queens last name (married) and birth last name and what the last names of her children are. I’ve watched several documentarys on the Queen and i find her to be a very gracious person. I understand sometimes the media can do her no justice by some of the things they say or report about her family,but i find her to be one who lets very little if any of these so called reporting to bother her. I myself have ancestors who came from England (as do most) and hopefully one day I can(soon) visit England and have the chance to meet the Queen.
Barbara
 
The Queen does not normally use a surname (she doesn’t need a passport or a driving licence for example), but on the few occasions where it has been necessary, i.e. when serving with the ATS during World War II, she has used the surname ‘Windsor’.
(source: www.royal.gov.uk)

The British royal family changed their last name from Saxe-Coburg-Gotha to Windsor in 1917.

Why did the Royal family change their last name?
The family name was changed as a result of anti-German feeling during the First World War, and the name Windsor was adopted after the Castle of the same name.

Windsor is still the official family name for any British royal who is styled “Royal Highness.”

Some members of the royal family have a different last name
From 8 February 1960, all The Queen’s descendants who do not bear the “style, title or attribute of HRH, and the titular dignity of Prince or Princess” have been givn the surname of Mountbatten-Windsor. (Mountbatten is the surname adopted by Prince Philip before his marriage).

(The queen’s youngest son, Prince Edward, the Earl of Wessex, has used the name Edward Windsor professionally. His wife, the Countess of Wessex, has been known professionally as Sophie Wessex.)

Unless The Prince of Wales chooses to alter the present decisions when he becomes king, he will continue to be of the House of Windsor and his grandchildren will use the surname Mountbatten-Windsor.

Interesting fact:
Before 1917, members of the British Royal Family had no surname, but only the name of the house or dynasty to which they belonged.