If you click the three dots on the top right of an ad in the newsfeed, you should be able to press 'Why am I seeing this' to see an explanation of the targeting for an ad. I can see one on my newsfeed that says:
> One reason you're seeing this ad is that Castore Sportswear wants to reach people who have visited their website or used one of their apps. This is based on customer information provided by Castore Sportswear.
> There may be other reasons you're seeing this ad, including that Castore Sportswear wants to reach people ages 18 and older who live in the United Kingdom. This is information based on your Facebook profile and where you've connected to the internet.
> One reason you're seeing this ad is that Castore Sportswear wants to reach people who have visited their website or used one of their apps. This is based on customer information provided by Castore Sportswear.
> There may be other reasons you're seeing this ad, including that Castore Sportswear wants to reach people ages 18 and older who live in the United Kingdom. This is information based on your Facebook profile and where you've connected to the internet.