(Justin Sullivan/Getty Images)

Starting Wednesday, Twitter will change its rules to prohibit users from posting of "revenge porn" -- intimate, and possibly explicit, images or video posted publicly without consent -- to its social network.

"You may not post intimate photos or videos that were taken or distributed without the subject's consent," says a new line in the company's list of community rules. Twitter has also updated its abuse policy to specifically mention "intimate photos or videos that were taken or distributed without the subject's consent," alongside its prohibitions against making threats due to a person's race, gender or age.

The San Francisco firm has been slow to respond to growing criticism that it has not done enough to prevent bad behavior on its site, but has recently rolled out several policy changes.The firm announced in August that it would take steps to improve user safety and combat harassment. It released smaller updates to its rules in December and February.

It's also become clear that addressing these concerns is a priority at the highest levels of the company. In a recently leaked memo, chief executive Dick Costolo acknowledged that Twitter is very bad "at dealing with abuse."

This latest move comes just a few weeks after reddit announced it would change its own policies to crack down on those who post unauthorized nude and explicit photos on its site. Several states, including California, have also considered or passed bills to directly address non-consensual pornography.

Under the new rules, Twitter users who see such photos of themselves posted online will be able to report the authorized material to the company. Only the subject of the photo -- or their legal representative -- is allowed to request that Twitter review and remove the pictures. Those who post the photos are allowed to appeal a takedown decision, if they feel it was unwarranted.

Unlike reddit policies, if Twitter employees determine a photo does violate the new rules, the firm will not only hide the post from public view, but also lock the account of the person who posted it.

"[Those] users will be required to delete the content in question before being able to return to the platform," the company said. Those who post content intending to harass others could be suspended from Twitter altogether. If the photos become the subject of a legal investigation, the company said that it will follow its existing rules if asked to turn over personal information on the person who posts the pictures.

But there are exceptions. For example, the company said: "Photos or video that do not appear to violate the policy -- such as content that an individual has previously indicated was made publicly available with permission -- will not be actioned."

Those who advocate on behalf of victims of abuse and domestic violence said that Twitter's new rules are a step in the right direction, and continue to help build momentum in fighting a peculiarly 21st century tactic of the long-standing problem of abuse.

"There’s a little bit of a tipping point," said Cindy Southworth of the National Network to End Domestic Violence. Having big corporations say they won't tolerate this kind of behavior helps, Southworth said, especially since the conventional wisdom has been that those who face abuse online should simply stay offline altogether.

"It is not okay to say the only way to be safe is to become socially isolated," she said. "Domestic violence is about isolation, and it's so important [for victims] to be able to reconnect with friends and family."

According to a recent survey of domestic abuse victims conducted by the NNEDV, 55 percent of programs that provide support for domestic violence victims reported that revenge porn was used to perpetuate abuse against those in their programs. The same survey found that 27 percent of the programs surveyed reported that abusers had used Twitter. (Nearly all, 99 percent, reported that Facebook, as the world's largest social network, had been used as a platform for abuse.)

Having the problem directly addressed by major technology firms is an enormous help for victims who often have a lot of trouble getting these pictures removed, said Christina Gagnier, an attorney specializing in privacy issues and board member of the non-profit privacy group Without My Consent.

"Though this might seem like just a couple of additional options to report abuse, it will have a big impact for victims," she said.

Yet while companies can provide immediate steps for online abuse victims, Gagnier said, they're only part of a lasting solution. Laws must also change to address the problem.

"We have been using really old laws that don’t address what’s happening," she said. "That makes it hard for judges and law enforcement" to address the issue.