Apple and Google phones now add location metadata by default to every photo taken with them. Social media apps then use this data when you share these photos.
Not only are you telling anyone who sees the photo and knows how to view metadata where you took the photo, but now several companies know where you have been if you give them access to your photos. If you share your photos on Facebook, Facebook can determine where you went on vacation, where you hang out with your friends, and where you take your kids to eat.
Sometimes these companies get it wrong, they may think you went somewhere when you were outside in the street or in a different business. Also they may assume that if you went to someone's house that has a home based business it will assume that the pictures belong to the business. The program will ask if you want to share Catherine's Tupperware photo, when it is just a photo at Catherine's house.
It will be interesting to see how these false associations are corrected. Using this location data from photos is probably only 80% accurate, since other people could use the phone and other issues mentioned earlier. Adding in the other information that these social media companies have, they can get a really accurate picture of you.
The location information on photos is just one more piece of the puzzle. These companies want to be able to sell their knowledge of you to marketers. This way the markets can develop ads which appeal to you.