A lot of users were angry at Twitter's unexpected experiment / EMMANUEL DUNAND/AFP/Getty Images

The change is intended to keep the site’s most important people engaged with it, according to reports

Twitter is experimenting with not showing ads to some of its most “high value” users.

Prominent and active Twitter users are either seeing a dramatically reduced number of ads, or no ads at all. And it is all part of Twitter’s plan to ensure that its most important users keep tweeting, according to reports.

For almost all of its users, Twitter displays ads alongside normal tweets. Companies can pay to have their own cards pushed into people’s timelines, and they appear alongside the people they follow.

But for the select few, those ads have been completely removed, according to reports. The ad-free Twitter accounts have been going on since September, when now permanent CEO Jack Dorsey took on the job on an interim basis.

The users that are chosen not to see ads aren’t necessarily celebrities or stars, according to Re/Code.

Instead, the accounts are chosen using a variety of criteria, including the number of tweets they post and how well those tweets are engaged with. It isn’t clear whether the feature is given only to verified users, though not all verified users have had ads removed.

Twitter generates almost all of its money from ads. But the site has had other problems, as well as its revenues, including a sliding share price and the recent departures of some of its most high-ranking staff.

Re/Code asked Twitter whether it was likely that the site might move to offer the ad-free experience to all users, if they pay a subscription fee. “We’re constantly looking at constraints and adjustments to optimize which ads are shown and how often,” a spokesperson told the site.