This document is meant to be a collection of commonly asked questions about Ad Groups in Twitter's Ads API.
Ad groups, known as line items in the Ads API, exist under campaigns and are used for targeting and bidding against a set of Twitter users. Advertisers promote Tweets or media (e.g., videos that are promoted as In-stream ads) by associating them with a line item.
Ad Groups are created by calling POST accounts/:account_id/line_items multiple times for the same campaign ID, and keeping (possibly completely different) targeting and Tweets associated with those line items. There is a limit of 100 line items per campaign and a limit of 200 active campaigns for a single ads account. Across all campaigns, there is a limit of and 8,000 active line items per ads account.
Ad Groups are intended to make it easier for advertisers to organize, optimize and manage their campaigns.
The advantage of Ad Groups is to compare and control different strategies across bid, budget, creative, and targeting. Upon associating multiple Promoted Tweets to a single line item, the auction would select the best Tweet from that group and then select the best Tweet for that campaign from all of the line items. If you have multiple Ad Groups with single Tweets, it would effectively select the Tweet that would likely perform better from that Ad Group.
Using Ad Groups enables an advertiser to split up targeting and bidding into a much greater number of possible combinations, and in general allows splitting up targeting into logical groups.
Ads API tools in particular could be built around fine tuned optimization rules with Ad Groups that would be more difficult to do via manual edits due to the larger scale of line item and creative combinations.
The total_budget_amount_local_micro for a line item cannot exceed the total budget for its parent campaign. Similarly, the line item’s bid_amount_local_micro value should not exceed daily_budget_amount_local_micro or total_budget_amount_local_micro of the parent campaign. Setting these values incorrectly may put the overall campaign into a paused and unservable state.
Note that the total campaign budget can be less than the sum of the budgets of its child line items, and distribution of budget between line items is partially up to the Ads API tool to effectively optimize and change as daily performance of targeting (line item) could differ significantly day to day due to Twitter’s realtime nature.
The performance of a campaign depends upon many factors and effectively a Tweet is the final deciding factor of performance. A Line Item will be treated as a factor of whether or not a Tweet is even in the running to be served to a user.
Line items that target the same sets of users are considered to have overlap of users. It is considered a best practice to reduce this overlap of targeting between line items so that the highest performing sets of users can be clearly identified.