Twitter has launched a "report tweet" feature aimed at helping people who receive abusive messages.
A number of womern were recently targeted on the site, including Walthamstow MP Stella Creasy. Over one hundred thousand people signed a petition to get the site to improve its procedures for dealing with abuse.
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George Michael died in December last year at the age of 53.
PC Keith Palmer, 48, stabbed by Khalid Masood while on duty in the grounds of the Palace of Westminster last Wednesday.
Those gathered on the bridge fell silent at 2.40pm - the time the first call was made to police exactly seven days ago.