Tiger The script counts the number of readers to each story and the stories with highest count will be in the "Overall Most Popular Stories". The "Recent Popular" is determined by the counts of current month.
The reader is counted only when he/she clicks in a chapter or the full text page. Seeing the reviews or synopsis pages will not be counted. A reader from the same IP address in the same day will be counted as 1.
How could a visitor cheat? He can read the same story from different computer (so different IP), or he can disconnect and re-establish internet connection if he has dynamic IP setting from ISP. He can also "write a totally nonsensical story and title it "Lesbian Snuff Queens Captured By Mind Stealers and Given to their Great Danes". But that story may not be posted at all. And the readers won't read it again the next day. If some reader is kind enough to notify me, that story will be gone very soon.
Considering 15,000 unique daily readers (they acturally read some story), the cheater will have hell a lot of work to do.
The stories can also be listed according to the ratings. It's hard to combine the story clicks and ratings to get a overall score, unless someone can come up a reasonable way to calculate.