Vanessa Friedman
Vanessa Friedman
ON THE RUNWAY

Officially, it’s the Metropolitan Museum of Art Costume Institute Benefit, a black-tie extravaganza held the first Monday in May to raise money for the Costume Institute (a.k.a. the fashion department), the only one of the Met’s curatorial departments that has to fund itself. Unofficially, Monday night’s festivities in New York have been called many things, including “the party of the year,” “the Oscars of the East Coast” (mostly because of the star quotient and the elaborate red carpet, in which guests pose on the grand entrance stairs to the museum) and, somewhat pointedly, “an A.T.M. for the Met,” by the publicist Paul Wilmot.

The party signals the opening of the Costume Institute’s annual blockbuster show, and it is known for its celebrity and fashion hosts. This year, the exhibit is “Manus x Machina: Fashion in an Age of Technology,” and the hosts are Anna Wintour, chairwoman of the gala; Jonathan Ive, chief design officer of Apple; Taylor Swift; and the actor Idris Elba. The honorary chairs are the Chanel designer Karl Lagerfeld; Miuccia Prada; and Nicolas Ghesquière, Louis Vuitton’s artistic director. All will be in attendance except for Mr. Lagerfeld, who will be in Cuba because the Chanel Cruise show is in Havana the day after the gala.

Why is it called the party of the year?

Ms. Wintour, the editor of American Vogue and the artistic director of Condé Nast, took over as chairwoman of the gala in 1999. Since then, she has been instrumental in transforming a local philanthropic event into the ultimate global celebrity/power cocktail: Take a jigger of famous names from fashion, add film, politics and business, and mix. It is among the hardest party tickets of the year to get — and thus intensely coveted.

How much does it cost?

Tickets this year are $30,000 apiece, and tables are $275,000. The party and exhibit are sponsored (this year Apple is the main underwriter), so all the money raised from ticket sales goes to the Costume Institute. Last year, more than $12.5 million was raised. Of course, not everyone pays for a ticket. Brands often invite celebrities to be their guests and sit at their table, and Ms. Wintour also often invites up-and-coming designers who might not be able to afford a ticket and scatters them around the event.

How many people attend?

Last year, there were about 600 attendees.

So if I can afford a ticket, can I go?

Dream on. Unlike other cultural fund-raisers, like the New York City Ballet gala or the Frick Collection’s Young Fellows Ball, the Met gala is invitation-only, and there is a waiting list to get on the invitation list. Qualifications for inclusion have to do with buzz and achievement (and beauty) more than money. Ms. Wintour has final say over every invitation and attendee, which means that even if a brand buys a table, it cannot choose everyone who sits at its table: The brand must clear it with her, and Vogue.

O.K., you’re saying I can’t go. So why should I care?

It’s reality TV at its most glamorous. Watch Justin Bieber schmooze with Rihanna! See Gisele Bündchen and Tom Brady greet Donatella Versace! Check out Chelsea Clinton kissing Diane von Furstenberg! Judge whether you approve of their outfits! You get the idea.

Speaking of outfits, do attendees have to dress in theme?

It isn’t explicitly stated that attendees have to dress like the exhibition, but it is encouraged. This can sometimes backfire. In 2013, for example, the theme was “Punk,” and the red carpet, which featured Sarah Jessica Parker in a Philip Treacy fauxhawk hat and graffiti gown, and Madonna in fishnet shorts and a studded plaid jacket, was widely panned.

Last year, the exhibit was “China: Through the Looking Glass,” and it created some politically incorrect moments when celebrities and the designers who dressed them got their Asian references muddled. (Lady Gaga, for example, wore a Balenciaga kimonolike look, which seemed to lean toward the Japanese; ditto Georgia May Jagger in Gucci.) Generally, it is advisable to play it safe and just get really, really dressed up.

That said, what is not negotiable is that if celebrities are invited to the gala by a brand, they have to wear clothes from that brand. This encourages brands to get the best celebrities because they can act as something of an advertisement for a house. It is also why, whenever designers are photographed on the red carpet, their “dates” are almost always famous people. Last year, for example, Marc Jacobs took Cher; Christopher Kane, FKA Twigs; Alexander Wang, Taraji P. Henson; and Jeremy Scott, Katy Perry.

This year, you can expect guests to be wearing a lot of Prada, Louis Vuitton and Chanel, given the honorary chairs, though the technology component could yield some interesting results. Beyoncé usually makes the final entrance, so it’s worth watching until the bitter end.

How long has this been going on?

The publicist Eleanor Lambert started the gala in 1948 as a typical philanthropic endeavor for the great and good of New York society. Pat Buckley, the wife of the conservative pundit William F. Buckley Jr., took over as chairwoman in 1979, but it has morphed into its current form only since the turn of the millennium. Ms. Wintour now oversees every detail, down to timed entrances for guests.

What happens when guests get inside?

It’s a secret! Since last year, posting on social media has been banned after the red carpet. What I can tell you is this: There is a receiving line inside with all the hosts, and guests have to file by and air-kiss them; then they tour the exhibit on their way to the cocktail party, so they are at least theoretically forced to see the culture. After cocktails, they are called in to dinner, and there is always some form of entertainment (last year, it was Rihanna; the year before, Frank Ocean). This is good, because as the red carpet part of the evening has become a giant marketing event — live streamed on a variety of sites, and shown on E!, just like the Oscars — the fact that the main part of the event is private allows guests to relax and have fun.

Or so they tell me.