Well, simply put, it's the strategy used to deliver your ads in the auction. Your ad impressions are impacted by your bid, as well as other factors like quality of your ads, relevancy, etc. So the strategy you choose can have a measurable impact on how your ads are delivered, and to whom, which will affect your business outcomes and overall performance.
What are the bidding strategy options?
There are 5 primary bidding strategies inside Facebook and Instagram Ads: