You can create custom segments in order to filter your audience when you send the campaigns. You can choose multiple conditions to create a segment (e.g. systems, browsers, devices, countries, sessions count, last visit, subscription date, sent messages count, delivered messages count, clicked messages count).
By default, every website has two built-in segments: All subscribers and Test subscribers.
Go to Sendflow platform
Go to Subscribers section
Click Create segment in top right corner
After you have created a segment, you can see the number of subscribers included in that segment in bottom of modal.
When creating the campaign you can send to all your subscribers or select the segments that interest you. That give you the ability to target subscribers with more personalized and more engaging web push notifications.