Today, Facebook announced a number of changes related to the use of Facebook and Instagram by children, including some changes affecting advertisers as well.  

Facebook said that, within the next few weeks, advertisers on Facebook, Instagram, and Messenger will only be allowed to target ads to people under 18 based on their age, gender, and location.  (This age cut-off will be higher in some countries.)  Facebook said, "This means that previously available targeting options, like those based on interests or on their activity on other apps and websites, will no longer be available to advertisers." 

Noting that it believes in showing people relevant ads so that they can discover and purchase products that are interesting to them, Facebook said that it already gives people ways to indicate that they would rather not see ads based on their interests or other activities, such as through Facebook's controls and settings.  Facebook acknowledged, however, that "we've heard from youth advocates that young people may not be well equipped to make these decisions.  We agree with them, which is why we're taking a more precautionary approach in how advertisers can reach young people with ads."  

Facebook said that when users reach age 18, Facebook will notify them about targeting options that advertisers can use to reach them and the tools that Facebook provides to allow them to control their ad experience.  (To be clear, in order to be join Facebook, users must be at least 13 years old.)