The Great Galactic Census is an event featuring the player minor factions in Elite Dangerous. Technically it is a statistical record and analyses of the population of PMF systems and supporters of these factions along with system statistics. However it serves a significantly broader range of goals and purposes in-game as well as supporting the game and it's community. You can read about the goals of the census in a nutshell in our infogram.
Even better you can gain insight into the census in the context of Elite Dangerous history from the The Great Galactic Census Motion Picture. The CEO of SSL Interstellar PLC has given an interview on The Great Galactic Census informing the public about the views and motives of the company regarding the census.
There is also a text version of the TGGC Motion Picture promoting the interests of Galactic Citizens. You can read the interim results of the census here, final results will be published after the sampling phase of the census will be completed in the 17th of July, 3304.
Entries from player minor factions are accepted in the sampling phase. If your appetite is already whet for joining the census with your player minor faction you can submit your entry in this form, but before you do that please have a look at the FAQ containing important information on setting the sampling date, taking a sample within a single BGS tick and obtaining your faction's consent.
The topic on the science, art and history of the Theta Region and SSL Interstellar PLC provides an overview of the host of the Great Galactic Census, including the activities and management procedures and infrastructure of the faction. More importantly this topic collects some of the contributions of SSL and it's members to the science, art, development, security and the community of the Elite Dangerous Galaxy.
Last, but not least stay tuned to a mid-census virtual event for player factions of Elite Dangerous. These player factions manage half of the inhabited systems of the Milky Way in Elite Dangerous and challenge the dangers of the Universe day after day, so they deserve the recognition and their actions and activities deserve publicity.