The Core Contest (TCC) is a short, intensive competition where participants focus on improving Wikipedia's most important articles, particularly those in the worst state of disrepair. Winners are chosen based on the "best additive encyclopedic value", and awarded cash prizes; this year, the prize money is £300 split between the winners.

A noble pursuit originally organised by Danny (talk · contribs) in 2007, TCC was revived in March 2012, and again in June 2021.

As Wikipedia has evolved and become more detailed and polished, its criteria for featured and good-article status have become more rigorous. This is a good thing as we are now producing an ever-expanding portfolio of material that actually looks like it could appear in a published tome. However, one side effect is the rigour of the process favours the production of more esoteric/narrow/specialised good and featured content. What to do? Carrots are always preferred to sticks, and so this competition fills a niche...

The aim of the contest is to encourage a short, sharp burst of activity and article improvement in the vital articles. Editors are also welcome to improve any broad or important article which lies outside this list as long as they explain why their article should be considered. The list provided is a guide only. Furthermore, a priority is to improve those core articles in the worst state of disrepair, expanded upon below:

• The article improvement process takes place over one and a half months, during which time an editor or editors knuckle down and improve an article, and submit a diff of their work at Wikipedia:The Core Contest/Entries.
• The broader or more "core" an article is, the greater weight it will be given in scoring. The general pool should come from Wikipedia:Vital articles. Anyone willing to tackle one of the top-tier vital articles will gain much kudos for it. Other broad articles can be nominated (see other lists of {{core topics}} for inspiration), as some important and broad articles are missing from the list above. Any editor is welcome to nominate any article and if they can put a good case as to why it should be considered; we'll certainly listen.
• During this period, prizes will be awarded to the best article improvement of a large/broad/important article. Improvement will be quantified and compared – in cases of similar levels of improvement, articles in a worse state to begin with will be deemed more valuable, all other parameters being equal. Thus an article that has gone from (say) 10–50% sourced with reliable sources, will be valued more highly than one from (say) 50–90% sourced.
• As judges review entries, they will post feedback on the improvements and areas still to improve before future good article nomination or featured article candidacy.
• Current featured articles are not eligible. Good articles are, but you might have a tough time showing radical improvement in a GA, which would most likely be dwarfed by massive improvement in a start-class article. The good- and featured-article process are not considered part of the Core Contest.
• The judges will weigh up the improvement of the article, combined with its "core-ness", to come up with a "best additive encyclopedic value" to Wikipedia.

Panel of judges – Casliber (talk · contribs), Femke (talk · contribs) and Aza24 (talk · contribs)

• Core Topics Collaboration, had a similar goal but no cash prize. It was active between 2006 and 2008.
• Discord/Team-B-Vital, Discord channel that tries to bring a vital article up to B-class each week, started 2021.
• WikiCup competition run over the course of a year tallying up improvements across the wiki, run every year since 2007.
• Meta — List of Wikipedias by sample of articles competition offers "virtual prizes" for improvements every month since 2009 (although the prize has never been won by en.wp so far).
• Other cash lures
  • Wikipedia:Reward board