Google is making a change to AdWords Display ad groups with no targeting options specified, starting January 11, 2017, "a Display ad group will be eligible to serve ads as soon as its status is set to ENABLED and it has a bid, a budget, and an approved ad," Google said.
As of now, ad groups in Display campaigns don't serve until at least one positive ad group targeting criterion, such as Placement or CriterionUserList is added to it. Google notes though this behavior worked well to target specific criteria on Display, but "not if your goal was to target as broad an audience as possible."
This change only impacts campaigns with AdvertisingChannelType of DISPLAY or VIDEO.
Adding, Google explains, "If an ad group doesn't have a ad group level positive targeting criteria," then "the ad group will target entire Display network, subject to exclusions and campaign-level targeting settings (such as geo, language, etc.)," with the potential to quickly exhaust a campaign budget.
Before this feature is enabled on your account, any existing Display ad groups without ad group level positive targeting criteria will be set to PAUSED.
For existing Display campaigns and ad groups, "If you want to target entire Display network (subject to exclusions and campaign-level targeting settings), then after the feature is enabled," make sure "you set those ad groups to ENABLED," since they will be in the PAUSED state.
Otherwise, "add the desired positive targeting criteria to each ad group, and then set it to ENABLED."
For new Display campaigns and ad groups, review your application's ad group creation workflow to ensure that it does, "sets the AdGroup status field to PAUSED when creating a new ad group via AdGroupService.mutate and an ADD operation." And, it "only sets AdGroup status to ENABLED after adding targeting criteria (if desired)."
You can update the status of your AdGroup via AdGroupService.mutate and a SET operation.
In addition, Google said, if an application adds and removes targeting criteria from existing Display ad groups, "make sure that it also properly update ad group's status to PAUSED or ENABLED" if the intended side-effect of criterion addition or removal is to pause or start serving.
"This is particularly important when removing the only positive criterion for an ad group, since this will change its reach from very narrow to very broad," writes Google.
If you are not aware, "an ad group contains one or more ads which target a shared set of keywords. You set a bid, or price, to be used when an ad group's keywords trigger an ad to appear. This is called a cost-per-click (CPC) bid. You can also set prices for individual keywords within the ad group. Use ad groups to organize your ads by a common theme, such as the types of products or services you want to advertise."