IMDb is an online database of movies, TV series, and video games. IMDb stands for Internet Movie Database. It includes information of the cast, biographies, production team, and summaries of plot, trivia, reviews and rating. The database itself does not rate movies. The rating you see on a movie on IMDb is made from reports gathered by the scores made by users of the platform.
It does this by weighing the average scores and not just the raw scores provided by users. Registered members of IMDb are able to cast their vote on any movie and then IMBb takes up the data and calculate the average score to give a single rating to a movie, video game, TV series, and so on. Hope you find this information helpful.