It was a holiday surprise that few anticipated, and even fewer appreciated, as Instagram changed its terms/conditions of service on Monday, Dec. 17. Before the announcement, 2012 had been a landmark year for the photo-sharing service: in April, the service was purchased by Facebook for $1 billion, seeing a proliferation of users. Publications like TIME, National Geographic and the New Yorker have integrated Instagram in their editorial work — TIME has twice featured Instagram photographs on our cover this year — once for our Wireless Issue and another to lead our print coverage of Hurricane Sandy.

Instagram’s strength lies in the application’s no-fuss, integrated and intuitive interface — camera software tied to your phone (and now your Facebook account) that allow users to visually document everything from important world events to their breakfast. But as photographers adopted Instagram for creative and even professional purposes, questions arose about ownership, property rights and profitability.

According to the changes, effective January 16, 2013, any photograph posted on Instagram’s service can be repackaged and sold by Instagram for advertising purposes without the user’s knowledge or consent. In addition, by agreeing to the new terms, users are responsible for any legal claims that may result from the promotion or use of their images.

Long story short: Instagram can use your content to increase their revenue, and if a legal claim is brought against the company regarding how these images have been used, you (the user) might be responsible for the damages.

—Adam McCauley

UPDATE (Tues, 5:25pm EST): Instagram has posted a statement responding to user feedback.

LightBox will be updating this post throughout the day as more photographers weigh in. What do you think? Let us know in the comments below.