Environment targeting options let you serve ads to online users surfing the World Wide Web and/or using mobile applications.
To restrict environments where your creatives may run, uncheck any environments you wish to exclude.
On websites
Web placements - Standard websites.
Mobile Web Placements - Websites optimized for browsers on mobile tablets and phones.
In apps
Mobile app placements - applications installed on mobile tablets and phones.
IMPORTANT: You can leave both options unchecked. If you leave both options un-checked Zemanta will consider targeting both environments.
Targeting Recommendations
To target in-app inventory, be sure that tablets and mobile phones are targeted in Devices targeting.
To target PC-based web placements exclusively, check On websites and uncheck mobile phones and tablets in Devices targeting.
To target mobile-based web placements exclusively, check On websites and uncheck desktop in Devices targeting.