The hacktivist online collective Anonymous is expecting thousands of people to march in cities across the globe on Thursday as part of its "Million Mask March."

According to the group, more than 670 cities are expected to host marches, and the theme of this year's march is "building a better future through collective action."

"While individual participants may have different ideas about what a better future looks like, they will be demonstrating together in support of Anonymous' methods and the continued ability for people to congregate under their banner and take actions anonymously," the group said in a press release.

One of the largest marches is expected to be in London, U.K. According to its Facebook page, 18,000 people are slated to attend the march in Trafalgar Square. 

On Facebook, the group says it stands against the "encroaching destruction" of civil liberties, pushes to make the Internet a part of the "surveillance state," and government disregard for migrants, the poor, the elderly and the disabled.

"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 Facebook page said.

Similar marches are set to take place in cities across Canada, including Toronto, Montreal, and Vancouver.

Canadian anthropologist and author Gabriella Coleman gained insider-access to the group by frequenting its chat rooms and online forums. She later wrote a book about what she learned titled "Hacker, Hoaxer, Whistleblower, Spy: The Many Faces of Anonymous."

She told CTV News Channel that she initially became interested in Anonymous after the group started to become involved in political activism.

"Originally the name was used primarily for pranking, sometimes humorous, sometimes vicious. It was a name that was not used for political purposes," she said. "And then in 2008, when anonymous targeted the Church of Scientology, an activist sensibility was awakened. That surprised me."

Over time, Coleman said she was able to interview Anonymous members, gain their trust and earn access to the "secret" nooks of the collective. She said she discovered that the group is much more diverse than she'd initially thought; admitting that she believed the group was mainly made up of "white, young, alienated males."

"They exist in Anonymous, but one of the fascinating things is that it's far more diverse than you might expect," she said, noting that she's met all types of members, including janitors, Buddhists, lawyers, the rich, and the poor.

"I think because no one knows who lies behind the mask it just attracts very different types of people."

She added that the collective is truly global, with smaller "nodes" in countries around the world.

In addition to protesting the Church of Scientology, Anonymous says it has helped to defend WikiLeaks, oppose Internet censorship in Australia and the U.K., as well as mass data collection in the U.S.

It also claims to have played instrumental roles in supporting the civil uprisings in Hong Kong, Tunisia, as well as the Occupy Movement.