Twitter said the ability to hide tweets would give users "more control" over their conversations. Critics of the move argue that such a feature would allow users to silence dissenting voices. But the platform believes that visibility of the hidden replies -- as well as the fact that anyone can view them -- will prevent it from becoming a proxy for censorship.

The platform's test of the tool in Canada has been encouraging. Users mostly hid replies that were irrelevant, abusive or intelligible. More than a quarter -- 27 percent -- of users who had their replies hidden said they would think about their actions in the future.

The "hide replies" feature isn't permanent. Based on the trial's outcome in the US and Japan, Twitter could decide to axe the feature.