A Block List is a .csv file listing apps, websites, and Pages within Facebook's Audience Network, Facebook In-Stream videos, and Facebook Instant Articles where you don't want your ads to run.
Block Lists are for advertisers who want to use these placements but have Brand Safety needs.
According to Facebook, Block Lists are better when blocking URLs at the account (or business) level.
Creating your Block list's CSV file
In a text editing software, paste the URL(s) you would like to block delivery to into column A.
To block a publisher across all placements, include all their URLs (Facebook Page URL, website URL, and any app store URLs).
Then save your list in the CSV or TXT format.
Uploading your list on Paragone
Once your block list(s) is ready, you can use them in your Paragone campaigns, by uploading them directly in the Campaign Creation Flow.
In the Audience step, you'll notice in the advanced options the section 'Block Lists':
Here, you can add a new blocklist on the right, opening a window looking like this:
Upload your file and give it a name, which will then appear in the drop-down list:
Select your list, and it will be added to your audience!
Below the Block Lists, you can see another drop-down, with Categories you can exclude from your audience. They work the same way Block Lists do but based on categories of applications and websites.
For instance, if you select the 'Dating' option in the list above, your ad will not appear on Audience Network placements, and Facebook Instant Articles related to Dating.