The reach objective allows you to show your ads to the maximum number of impressions in your targeted audience at the most efficient price. Reach campaigns help raise awareness for your product/service to large audiences.
When you set up a campaign with a reach objective, you will need to consider:
Your marketing goal
How often you want users to see your ad
How much you are willing to pay for impressions
Frequency control allows you to manage exposure to your messaging. When you run a campaign with the reach objective, the bidding method is CPM, the price you are willing to pay for one thousand impressions.