[Britain’s shock vote brings swift consequences as leader to resign]

Meanwhile, Britain has not yet triggered Article 50 — the procedure for actually leaving the E.U. — and there are signs it may try to delay doing so as long as possible. If there is a general election, how and when to leave the E.U. would probably become a major issue.

Even when Article 50 is invoked, negotiations may take up to two years. Any new deal with the E.U. will have to pass Parliament. Some in Westminster are saying that it should probably be put to referendum again. If that happens, it may well be the last chance for "remain" to have their voice heard.

Britons react to cutting ties with the European Union

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Many celebrated the referendum results Friday and British Prime Minister David Cameron announced that he will resign after Britons went to the polls the day before.

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Would break from Brussels also splinter Britain? Probably not.

The British are frantically Googling what the E.U. is, hours after voting to leave it

Anger on the streets of London after Britain votes to leave the European Union

What will happen now that Britain has voted to leave the E.U.

Correction: An earlier version of this story said the petition was started on Friday. However, it appears to have been created in May, although it only reached its heights of popularity after the vote on Thursday.