The Internet Movie Database (known as IMDb) is a great online tool to be used by those who want to know more about a film they enjoyed watching; and I use the past tense here because although it could be a reliable website to find out if we will enjoy the film or not, those who really hate spoilers can easily find them.
Due to the #passionate way most reviews are done by the fans (registered users), we have various insights about the film, and what is so good about it that makes it worth watching (and what could be better), but most of the time these reviews are so thorough that we can easily get a lot of information which we would like to have found out ourselves, while watching the #film in question.
Although all data is checked before going online, some occasional errors are acknowledged from time to time and (when reported) are immediately taken care of, which means that it is a fairly accurate online tool. However, its most #controversial feature will always be the rating system: registered users are invited to rate any film on a scale of 1 to 10, and online filters make sure that fans only vote once. Like anything else based on popular opinion, heated debates do happen among users (which IMDb also stimulates) and many unpopular films are indeed great ones worth watching.
In my opinion, the best way we can use the IMDb website is to read the 'Did You Know?' section after watching an 80's or 90's (or even 00's) film. It is done so accurately and passionately that we will learn a lot about what happened behind the curtains, i.e. if the actors had real chemistry or despised each other, if it was the last time a director and an actor worked together, and even what they have written in their autobiographies about the film.