Thousands are expected to descend on London's Trafalgar Square to attend the Million Mask March.
What is the Million Mask March?
Associated with the hacktivist group Anonymous, Million Mask March protesters worldwide have rallied every year since 2013 against militarisation and police brutality and for self-governance.
In a 27-minute message posted to YouTube in the run-up to the 2017 event, Anonymous said: "Every November 5, the Million Mask March is a sign that humanity around the world is crying out for change."
Protesters usually wear masks depicting Guy Fawkes.
Who was Guy Fawkes?
Guy Fawkes, also known as Guido Fawkes, was a member of the English Catholics who planned the Gunpowder Plot of 1605.
The group wanted to blow up the House of Lords but ultimately failed. Guy Fawkes and three other plotters were hanged and quartered on January 31, 1606.
Guy Fawkes Night is celebrated across Britain, with revellers setting off fireworks and burning a Guy Fawkes effigy on a bonfire. The festival, which had Protestant spirit, started as a way to give thanks because the Gunpowder Plot failed but later fuelled anti-Catholic bigotry.
When will the Million Mask March take place?
The main march is expected to take place on Sunday, November 5 at 6pm (18:00GMT) at Trafalgar Square in central London.
The annual event coincides with Guy Fawkes Night. Police have said the march must end by 9pm. There is also an event planned in Barcelona, according to social media.
Is violence expected at Sunday's rally?
Thousands usually take part in the march, and there is usually some disruption. Last year, dozens were arrested.
Police have imposed a series of conditions on protesters. If, for example, demonstrators stray from the march route, they face arrest.
"We have strong reasons to believe that peaceful protest is the last thing on the minds of some of those who will attend," said Chief Superintendent Elaine Van-Orden.
"Criminality at the event has increased year-on-year. Arrests have increased from four in 2012 to 53 in 2016," she added.
British media reports say police will ramp up the use of body cameras to monitor violence.
What is the focus of this year's rally?
More than 1,000 people have expressed interest in attending the London rally on a Facebook page.
"We have seen the pushes to make the internet yet another part of the surveillance state, we have seen the government's disregard for migrants, for the poor, the elderly and the disabled," organisers said.
"We have seen the capital, profit and greed of the few put before the well-being of the many and we say enough is enough.
"The government and the 1 percent have played their hand, now it is time to play ours."
The rally is expected to be live-streamed and will be available to watch online.
Source: Al Jazeera News