While the costumes, toys, celebrities and comic books are easy to explain, it is the sheer scale of Comic-Con that defies description.
After four-and-a-half days, the world's pre-eminent "comic book convention" - translation: pop culture festival - has drawn to a close, as the last of some 130,000 exhausted people file out of the San Diego Convention Centre and board trains, plains and automobiles for home.
In their bags and backpacks they have a host of toys and treats, "exclusives" offered for sale only at the convention, and a host of memories of meeting their idols from Sherlock's Benedict Cumberbatch, to Iron Man's Robert Downey Jr and the iconic Superman himself, actor Henry Cavill.
Comic-Con may offer the best (and worst) toys, more comic books than you have ever seen in the one place and queues that would challenge even the most determined, but what it offers that no other event has is first-hand access, for fans, to the biggest names in TV and film.
And they came by the busload: Ben Affleck (Batman), Henry Cavill (Superman) and Gal Gadot (Wonder Woman) to promote Batman v Superman: Dawn of Justice, Matthew McConaughey and Christopher Nolan to talk about Interstellar and Colin Firth for Kingsman: The Secret Service.
Marvel wheeled out the entire cast of Avengers: Age of Ultron: Robert Downey Jr, Jeremy Renner, Mark Ruffalo, Chris Hemsworth, Samuel L. Jackson, Chris Evans and Josh Brolin among them.
The casts of Sons of Anarchy, Grimm, Bates Motel, Supernatural, Arrow, Once Upon A Time, Game of Thrones and many other TV programs came, as well as the casts of new series such as Guillermo Del Toro's The Strain, the buzzy Warner Bros Batman origin drama Gotham and the highly-anticipated spin-off to Arrow, The Flash.
And flying the Australian flag were actors Adelaide Kane (Reign), Travis Fimmel (The Vikings), Phoebe Tonkin (The Originals), Brenton Thwaites (The Giver), Emilie de Ravin (Once Upon A Time) and Chris Hemsworth (Avengers: Age of Ultron). New Zealand actors Grant Bowler (Defiance) and Antony Starr (Banshee) were also there.
Celebrities making public appearances is nothing new, but what sets Comic-Con apart is the proximity it offers: here the stars sign autographs, pose for photos and fan videos, take questions from fans during Q&A "panels" and get pushed through a media factory in backstage "press rooms".
Compared to the high level of control usually exercised by Hollywood studios, Comic-Con is loose and fast. And Hollywood plays along because the value added to a film, television or gaming brand by its presence at Comic-Con is, usually, worth the few bruises it brings.
To the convention's credit, VIP passes to panels are precious few, preventing a squeeze on access to the stars, and keeping the convention focused on the market it is pitched at: diehard genre fans.
Among the highlights were glimpses of the reboot of the iconic Australian film Mad Max and the superhero juggernaut Batman v Superman: Dawn of Justice.
Fans were also treated to a first look at scenes from The Giver, introduced by its Australian director Phil Noyce, who appeared via video link, as he is in New York finishing the film.
Peter Jackson and the cast of The Hobbit: The Battle of the Five Armies, including Cate Blanchett, Andy Serkis, Benedict Cumberbatch, Lee Pace, Luke Evans, Elijah Wood, Graham McTavish, Evangeline Lilly and Orlando Bloom, also appeared at what may be their last Comic-Con appearance. To say goodbye - or alámenë, as the Elves would put it.
Not every headline was positive, however.
A 64-year-old woman injured her arm after being struck by a car travelling at low speed that was caught up in the convention's annual "zombie walk", in which fans dress up as zombies, complete with detailed "gory" makeup, and walk the streets in packs, grunting and moaning at passers-by.
When the car, containing a 48-year-old deaf man and his children, was surrounded by zombies, the children panicked, prompting the driver to nudge the car through the crowd to escape.
The incident worsened when the "zombies" began banging on the car windows and, at one point, attempted to open the car doors. A police spokesman said the entire family was deaf and the children had been scared by the zombie walk.
Comic-Con's organisers have not commented on the incident, though it highlights the fact not everyone in San Diego - a city of 1.3 million people - is aware of, or excited by, Comic-Con and the antics of its attendees.
Most "stunts" are more benign, such as 20th Century Fox's "Oculus Rift" Sleepy Hollow experience, in which fans could be filmed on green screen for a scene in which they were beheaded and a "slide" by a group of fans dresses as horror movie icon Michael Myers, the killer from the Halloween franchise.
Even the retail side of Comic-Con is not without its challenges.
Though many of the "exclusives" offered are intended to generate fan buzz and reward the brave and the exhausted for queuing at dawn, the sight of people dragging huge bags of toys to the shipping desk in the convention centre is common, and many of Comic-Con's gems end up on eBay for resale.
At the time of writing, there were more than 7000 eBay listings for "Comic-Con exclusive" and the 1966-era Lego Batmobile, of which only 250 were sold at the Lego stand every day for $US40, is selling on eBay for upwards of $US200-$US300. You have to admire the entrepreneurial spirit, but who's winning here: the fans, or the scalpers?
Though the numbers are difficult to pin down, and those who are responsible for releasing them prone to hyperbole, this appears to be the crunched data: the convention draws roughly 130,000 people and brings US$175 million ($186 million) to San Diego's economy, which includes about US$2.5 million in tax revenue and about US$78 million spent on site. The balance is corporate sponsorship, events and hotels, general retail and restaurants.
Whichever way you look at it, it's lucrative. And other cities, notably Los Angeles, have acknowledged publicly they would very much like to take it off San Diego's hands.
Though the convention centre in San Diego (and its neighbouring properties, the Hilton and Marriott hotels, which also stage events) are splitting at the seams, sentimentality appears to be the glue that holds it firmly in San Diego's hands.
Expansion is inevitable, particularly as Comic-Con's importance in the entertainment calendar grows, but to take Comic-Con away from the city where it began, with those few hundred fans in a building basement in 1970, would seem to be a transgression too great to bear.
For now.
 
 
