Twitter has revealed details about its recent rate limits, saying it was a necessary measure to combat bots and spam accounts.

The social media company angered users by limiting the number of tweets users could read, as well as preventing people form reading anything at all unless they were logged in. In a blog post, the company revealed its reasons behind the move:

To ensure the authenticity of our user base we must take extreme measures to remove spam and bots from our platform. That’s why we temporarily limited usage so we could detect and eliminate bots and other bad actors that are harming the platform.

The company also provided an explanation for why there was no advance notice:

Any advance notice on these actions would have allowed bad actors to alter their behavior to evade detection.

Twitter says it is working to address these issues on a broader level:

At a high level, we are working to prevent these accounts from 1) scraping people’s public Twitter data to build AI models and 2) manipulating people and conversation on the platform in various ways.

Currently, the restrictions affect a small percentage of people using the platform, and we will provide an update when the work is complete. As it relates to our customers, effects on advertising have been minimal.