User-generated content (UGC) is defined as "any form of content such as blogs, wikis, discussion forums, posts, chats, tweets, podcasts, 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 is also called user-created content (UCC). The term and concept 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, entertainment, advertising, gossip and research. It is an example of the democratization of content production; whereas during the 1970s and 1980s, traditional "gatekeepers" such as newspaper editors, publishers and news shows approved all content and information before it was aired or published, in the 1990s and 2000s, as media production through new technologies has become more accessible, user friendly and affordable to the general public, large numbers of amateur individuals are able to post text, digital photos and digital videos online, with little or no "gatekeepers" or filters. 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 user bases have grown on social media and content-based sharing sites.