ExpressionCargo Adware
ExpressionCargo is the randomly chosen name for a piece of Mac adware. The ExpressionCargo application belongs to the AdLoad family of Mac adware.
ExpressionCargo belongs to a long-running string of essentially the same piece of adware, repackaged using a different name. The naming convention used is simple - string two random words together, getting something like the name "ExpressionCargo". The icon used is always the same too - a looking glass image on a colored circle.
What those apps also have in common is their ability to push ads on your Mac. The main issue with this is that a lot of those ads can be sourced from rogue ad networks and may refer to misleading pages, untrustworthy websites, adult content and potentially unwanted apps.
This behavior is very obviously not desirable, as is the case with all adware. The ads served are not there to help you find better deals or new content, their only purpose is to generate revenue for the adware's author.
Luckily, similar apps are easily removed from your Mac, following standard uninstall procedure, and rarely have any meaningful persistence mechanisms.