Short answers, pulled from the story.
Rotten Tomatoes launched on the 12th of August 1998 as a spare-time project by Senh Duong. He was an undergraduate student at the University of California, Berkeley when he began coding the site in just two weeks.
The system calculates the percentage of positive reviews known as the Tomatometer score to determine film status. Films with 60% or more positive reviews are considered fresh while those below 60% receive a rotten designation.
In June 2004 IGN Entertainment acquired Rotten Tomatoes for an undisclosed sum. Warner Bros. then acquired Rotten Tomatoes in 2011 while retaining a minority stake in the merged entities before Comcast's Fandango Media purchased both Rotten Tomatoes and its parent site Flixster in February 2016.
Major Hollywood studios view Rotten Tomatoes as a potential threat to their marketing strategies because research found seven out of ten people less interested seeing films if scores fell below 25%. Some studios embargoed early critic screenings responding to poor reviews affecting pre-sales and opening weekend numbers.
On the 24th of May 2019 Rotten Tomatoes introduced verified ratings replacing earlier systems requiring mere registration. Users now verify ticket purchases through Fandango Media to have their reviews count toward displayed averages.