The “Search Network with Display Expansion” is a combination of Search Network and Display Network AdWords campaign types. With this campaign type your ads can show with search results on the Search Network, as well as in relevant placements within the Display Network. This campaign can help grow your audience and help reach potential customers early on in the buying cycle.
This type of campaign is set up similar to a Search Network campaign; budget, relevant keywords, ads & bids. However, ads are shown selectively on the Display Network & bidding is automated; this is to help reach people who are most likely to be interested in what is being advertised. Your ads will show primarily on the Search Network and will show on the Display Network if there is room in the budget.