User-generated content (UGC) is defined as "any form of content such as blogs, wikis, discussion forums, posts, chats, tweets, podcasting, pins, digital images, video, audio files, advertisements and other forms of media that was created by users of an online system or service, often made available via social media websites". It entered mainstream usage during 2005, having arisen in web publishing and new media content production circles. It is used for a wide range of applications, including problem processing, news, gossip and research and reflects the expansion of media production through new technologies that are accessible and affordable to the general public. Additionally, user-generated content may also employ a combination of open source, free software, and flexible licensing or related agreements to further reduce the barriers to collaboration, skill-building and discovery ("'UGC'") has also gained in popularity over the last decade, as userbases have grown on social media and content-based sharing sites.