Using tags to index social media content makes it more accessible. Example of a rose micrograph uploaded to the photo sharing website Flickr (http://www.flickr.com). (A) Besides a meaningful title and image description, tags (= keywords) further extend the accessibility of a photo. In this case, appropriate tags would be ‘rose’, ‘microscope’, ‘microscopy’, ‘leaf’ or ‘plant’. (B) The search term ‘rose microscopy’ displays all Flickr photos carrying these specific tags.