Twitter is not known as a forgiving place for politicians.
Ed Balls, for one, will never be allowed to forget the moment he tweeted the words "Ed Balls".
Since the first MPs started tweeting more than a decade ago, it has been a constant source of trouble, especially for those who make embarrassing blunders.
But what did today's major players have to say in their first tweets? Here is a selection from 20 of Westminster's most influential MPs.
Theresa May:
Jeremy Corbyn:
Jacob Rees-Mogg:
John McDonnell:
Boris Johnson:
Tom Watson:
Andrea Leadsom:
Emily Thornberry:
Anna Soubry:
Diane Abbott:
Michael Gove:
Caroline Lucas:
Philip Hammond:
Chuka Umunna:
Sajid Javid:
Luciana Berger:
Amber Rudd:
Yvette Cooper:
Jeremy Hunt:
Jess Phillips:
