Bot filtering allows you to filter events by sending user agents to Optimizely with your events. Optimizely will compare the list of user agents you send to a list of known bots, and filter all user agents that are on the IAB/ABC blacklist.
## Enable bot filtering
Navigate to _Settings_ > _Advanced_ > _Bot Filtering_ in the Optimizely app to turn bot filtering on or off. For more information, see our KB article [Bot and spider filtering in Optimizely](🔗).
## All other Full Stack events
When you track events with an SDK from somewhere other than a web browser, you must pass the user agent to be filtered with your event. You should pass it using the reserved `
$opt_user_agent` attribute in the [Track](🔗), [Activate](🔗), [Is Feature Enabled](🔗), and [Get Enabled Features](🔗) functions. If bot filtering is enabled for your project and the user agent is passed in this way, Optimizely applies bot filtering.
**Enable bot filtering in Optimizely first**. Before implementing the `
$opt_user_agent` attribute, navigate to _Settings_ > _Advanced_ in the Optimizely app to turn bot filtering on or off.
The example below shows how to pass the `