What is the IMDb top 250?

Dad has asked me what the Internet Movie Database Top 250 is and how movies get on it. Here is what Wikipedia says it is:

The IMDb Top 250 is intended to be a listing the top 'rated' 250 films, based on ratings by the registered users of IMDb.com using the methods described on the website. Only theatrical releases running longer than sixty minutes with over 1300 ratings are considered; all other products are ineligible. Also, the 'top 250' rating is based on only the ratings of "regular voters" (IMDb does not define this term). In addition to other weightings, the top 250 films are also based on a weighted rating formula referred to in actuarial science as a credibility formula. This label arises because a statistic is taken to be more credible the greater the number of individual pieces of information; in this case from eligible users who submit ratings.

The top 250 list comprises a wide strata of films, including major releases, cult films, independent films, critically acclaimed films, silent films and foreign films. Nevertheless, there are issues associated with compiling such lists of rankings which arise from the shortcomings of the approach to ratings.

IMDb indicates that submitted ratings are filtered and weighted in various ways in order to produce a weighted that is displayed for each film, series, and so on. It states that filters are used to avoid "vote stuffing"; the method is not described in detail, to avoid attempts to circumvent it.

Simple right? I am the first to admit the the list is completely and absulutely subjective. Basically anybody can vote for any movie at any time from when the movie opens to 80 years from now. So longevity is not a factor as long as the movie has the required amount of votes. That vote goes into a rating for each movie. If a movie gets enough votes from "regular users" it qualifies for the Top 250 list. But it can go both ways, if a movie gets lower ratings it can drop off the list. Old movies get on the list because voting is dynamic, I could go in and vote for Birth of a Nation and if my voting pushs it over the top, it would join the list (although I am not a "regular voter" by any means.) That doesn't really explain it, but IMDb keeps it ambiguous to prevent people from fiddling with the results. Did that help any at all?