On TV, the concept of "popularity" is easy to measure and hard to understand.
In music, the most popular songs are inescapable, and their artists become national celebrities. In movies, the most popular films are feted in the Monday papers and widely acknowledged, even if they only compete for the special-effects awards in March. But on television, the world of criticism and the world of viewership aren't merely askew; they're mostly on different planets. No self-respecting TV critic writes about NCIS: Los Angeles, ever—ever—even though the all-time most-popular episode of Game of Thrones (which is, itself, the all-time most-popular HBO show) got fewer viewers than an NCIS: LA rerun. As I wrote a few months ago, the most essayed-about show (Girls), most tweeted-about show (Pretty Little Liars), and most buzzed-about show (at the time: House of Cards) sum to half the average audience of NCIS (which is hardly essayed, tweeted, or buzzed about at all).
More than other entertainment industries, TV seems to play by the rules of a peculiar Faustian bargain: Be popular and scarcely acknowledged; or be praised and scarcely watched.
This bring us to The Big Bang Theory, which deserves a theory of its own. The Big Bang Theory is not merely the most popular comedy on television, besting its nearest rival by a margin of 10 million viewers. It's the most popular comedy for every demographic between the ages of 12 and 54 and, more importantly, the most popular show on television in 2014. An estimated 84 million people—equal to the combined populations of California, Texas, and New York—have watched at least six minutes of it this year, according to a marvelous new investigation of the show's popularity in New York magazine.