Shortly after the Sewol ferry sank in April, South Korean authorities hurriedly combed the messages and photos stored in the victims' Kakao Talk chats to learn more about the tragic sinking.
One might wonder how such a probe was made possible, given that the victims were still missing. The fact was that Kakao Talk stores users' private messages for about a week on its own server. Through a search warrant, the police could scrutinize private messages.
The implication is, if anything, unnerving. More than 90 per cent of smartphone users here have installed Kakao Talk and continually share texts, photos and videos with their friends and family members, generating a massive amount of data vulnerable to being accessed by the authorities.
Uninstalling the app would not sufficiently protect one's online privacy in this increasingly interconnected digital era.
People around the world continue to share their personal information via social media, and there is no sign of the trend reversing its course despite the growing concerns about online privacy.
One concern is that industry giants like Google and Facebook could use their huge databases for commercial and other purposes, while users have little clue about how their personal profiles and digital footprints are stored, handled and traded.
But social media networks are only a part of the digital spectrum in which people share their own information willingly or unwittingly. Online marketers and data brokers gather a huge amount of personal data by tracking digital footprints, which are left behind as a result of Web browsing and stored in the form of cookies.
How much user information is being handled by data brokers and trackers? A ballpark figure was offered by investigative journalist Julia Angwin, who said in a feature in CBS' "60 Minutes" news magazine that she tracked down 200-plus data brokers that held information on her and asked that it be deleted.