The TeamLiquid Map Contest (TLMC) is the official system by which StarCraft 2 Community Mapmakers can submit their work to and compete in it to have the chance to have their maps selected to enter into the official StarCraft 2 ladder map pool.
Over the years it has been clearly to all levels of the SC2 community that a dedicated group of Community Mapmakers can deliver a more consistent, balanced and interested set of maps than what a internal to Blizzard team could, as these Community Mapmakers have freer communication lines with all levels of the broader SC2 community and find themselves in a friction-less environment which allows them to iterate much faster on potential issues or new ideas than internal isolated groups at Blizzard can.
These realizations have led to the creation and consistent celebration of the TLMC’s, of which I am a proud part of serving as Assistant Administrator, Map Judge and Lead Quality Assurance for.
For further reading I very much recommend reviewing the Liquipedia page on the TeamLiquid Map Contests, where all the finalists have been painstakingly detailed.
For commentary, feedback and other extra bits, I highly recommend visiting my YouTube Channel where hours and hours of Level Design discussion have been logged!