Interest Targeting

Interest targeting shows your ad to people X has sorted into topic categories from what they engage with.

You pick from X's list of interest categories, and X serves people it has placed in those buckets based on their follows, reposts, clicks, and posts. It is the broadest way to select an audience, layered with everything else you set.

Say you sell camera gear and pick "photography" and "technology". X serves the large pool of people it tags with those interests, which is wide reach with loose intent. Add a location or a set of keywords on top and watch how far the estimated audience shrinks.

Interest is the widest, loosest layer. These categories are broad by design, so interest alone reaches a big, unqualified pool. Interest and follower selections stack as an "or", so each one you add makes the audience larger, not tighter.

Wide net, so narrow it with something else.