Yes - Everyone means every contact in the database with or without tags applied - so if you have chosen this option as shown below the email campaign will be sent to every contact in your database with an email address.
If you want to send to ONLY contacts with tags then you need to select the tags and the option will change to 'Just these tags'
If you want to send to ONLY contacts with tags but exclude certain tags then click on all the tag names you wish to send out to but make sure that you do not select the tag groups you wish to exclude from the send as shown below:
You can also select the choice Everyone except these tags and once again use the tag groups list to select the tag groups who you do not want to receive the email campaign as shown below:
If you use this option then it will send the email campaign to EVERYONE (tagged or not tagged) except for the tags you have selected to be excluded.
Please click here to read our guide on how to send out an email campaign.