Last month, when "Glee" packed an entire episode with Britney Spears songs (and [article id="1649055"]one Paramore tune[/article]), the show not only posted [article id="1648982"]record-setting ratings[/article], but placed a rather formidable stranglehold on the iTunes songs chart too. The following week, they decided to work a selection from the hallowed Lennon/McCartney songbook -- "I Want to Hold Your Hand" -- into things, a move that was equal parts cross-generational marketing masterstroke and, well, fist-thrusting victory lap.

Because, over the course of two-and-a-quarter seasons, "Glee" has transformed itself from a cult curiosity into to a bona fide sensation. It has spawned [article id="1639735"]sold-out tours[/article] and [article id="1640072"]chart-topping albums[/article], but now, it's become something else entirely: the kind of show that can feature songs by the greatest pop star of the past decade one week and the greatest band of all time the next. It's a genuine, market-driving, industry-rejuvenating hit. And how did all this happen? Well, because certain folks realized that there was money to be made in partnering with the show.

"The industry has definitely started paying attention. If you're a songwriter or music publisher, you're definitely promoting your songs to the show," said Jeff Brabec, vice president of business affairs for music publisher Chrysalis, which has landed songs by the likes of Billy Idol and Paul Anka on "Glee." "It's truly something different, because, of course, there are downloads, and the albums, which have been phenomenally successful, especially for TV soundtracks, but ... there are so many other opportunities [the show] presents. For a songwriter or a music publisher, 'Glee' is a goldmine. It touches almost every single source of income that's possible."

"A show like 'Glee' only comes along once in a blue moon, and it's just such a great platform for our copyrights," added Wende Crowley, vice president of film and TV music for publisher Sony/ATV, which controls not only the bulk of the Lennon/McCartney songbook, but also the songs of Bruce Springsteen, Taylor Swift and Lady Gaga, to name just a few. "It's not only embraced artists like Gaga, who are so huge in the collective consciousness, but it's breathed life into older songs too. It's been an amazing opportunity to work with them, and you wish more shows like it would come out each year. 'Glee' is a total game changer."

And while that may be the case, behind the scenes, the "Glee" machine runs on decidedly old-school fuel -- namely, music licensing: a dicey, downright confusing (and supremely profitable) area that the casual Britney fan probably can't even begin to comprehend. But, suffice it to say, when the "Glee" producers decided to use [article id="1648932"]" ... Baby One More Time,"[/article] they had to pay a lot. And before a single note of the song can be re-recorded, those payments begin with a synchronization license.

"Every time a song is put into a TV show, the producer has to sign a synchronization license to get permission to use [it], and it's a purely negotiated license," explained Brabec, who, along with his brother Todd, wrote an entire book on this very subject, "Music, Money and Success." "[The producers] send you a request that lists the use of the song and, in this case, the scene description, and they give you a number of options, with respect to how they want to distribute the show, and all have various price points. The publisher fills in the blank lines next to the dollar signs. ... You can make a substantial amount of money just in the synchronization fee alone. And that's just step one."

Admittedly, that's a pretty simplified explanation -- we glossed over stuff like "five-year, all-TV licenses" and "out-of-context trailer licenses" -- but after the sync license is signed, the ball is put in motion. Once an episode of "Glee" airs, the next step of the process begins, because now, a songwriter and publisher are reaping the rewards of not only iTunes downloads and album sales, but international re-airings of the show too. As you can imagine, this is where the real money starts to roll in -- and it's all guaranteed under a mechanical license.

"Immediately, you've got the download situation. Under that situation, the songwriters and music publisher, for every single download, will get 9.1 cents. So if a song is downloaded 100,000 times in the first couple of days -- and that's not unusual at all -- the music publisher will get $9,100 and the publisher will share that with the songwriter," Brabec said. "And then, extend that to the physical albums. If you've got one song on the 'Glee' album, and that album sold 1 million units, that would be $91,000 in songwriter and music-publisher royalty.

"And that's all backend. These things go on and on, years after your initial downloads. ... If a song is sung by the 'Glee' cast, you're probably looking at $900 to $1,100 for one performance on the Fox network. And that's U.S. only. This show is broadcast or repeated worldwide; you collect on that too," Brabec added. "And then you've got the ringtone market. If the 'Glee' version is on a ringtone, the songwriter and music publisher will get 24 cents for each ring tone distributed -- and then you've got sheet music, etc. Believe me, for years and years and years into the future, songwriters and music publishers will be making money on this."

So the bottom line is, if you're someone like Max Martin, and you wrote " ... Baby One More Time," well, chances are, you're loving life even more these days (and for the foreseeable future too). But the beauty of "Glee" is, you don't have to be a certified hitmaker (or even the Beatles) to benefit. Business is booming, and it doesn't show signs of slowing down anytime soon.

"When you have a song that appears on 'Glee,' the next day, it's on iTunes, and the number of downloads is astronomical, and it really reawakens people's interest in songs," said Kristin Durie, vice president of film and TV at EMI Music Publishing. "I think hearing these songs -- both old and new -- from 'Over the Rainbow' to 'Empire State of Mind,' is breathing new life into people's songs."

Have you downloaded any songs after watching an episode of "Glee"? Let us know in the comments!