Modern smartphones and cameras can add additional information to digital photos they create – date and time, camera model, and lot’s of other information, including GPS coordinates of place where photo has been made. When you upload such photo to your favorite social network it might either display this info explicitly, or just leave it intact and any user who’s watching it can find you on a map. Security experts are particularly worried about the pictures posted on social networks, since they are usually accompanied by real-time statuses.
Source: https://thehackernews.com/2012/03/potential-security-risk-of-geotagging.html