What is the Met Gala? 5 things to know

The annual private event, sometimes called the Met Ball, has been happening since 1948. Here are some things to know about the gala:

High society fundraiser

The Met Gala first held in 1948 by fashion publicist and Council of Fashion Designers of America founder Eleanor Lambert. Invited guests paid $50 for a ticket to attend a midnight dinner dubbed "The Party of the Year." They were held in December as an annual fundraiser for the Costume Institute, which became part of the Met in 1946. At the time, it wasn't as flashy as it is today; dinners were held at places such as the Waldorf Astoria, Central Park and the Rainbow Room.

One-of-a-kind party

The elaborate celebration the Met Gala is known for today didn't come to fruition until the early '70s, when former Vogue editor Diana Vreeland joined as a special consultant. Themes, from "The World of Balenciaga" to "The Age of Napoleon," became part of the gala and notable celebrities, such as Andy Warhol and Diana Ross, were invited along with politicians like Henry Kissinger and Jacqueline Kennedy Onassis. Vreeland was at the helm of the gala until her death in 1989.

Related: Anna Wintour: What to know about the Vogue editor

Vogue editor-in-chief Anna Wintour became co-chair of the gala in 1995, overseeing the gathering since then, except for the events in 1996 and 1998.

Invite-only

Just as it was in 1948, the Met Gala remains an invite-only event, there is a waiting list, and some have to pay for a ticket. Wintour, does much of the inviting. The exhibit and party itself are sponsored, so all the money from ticket sales goes to the Costume Institute. Tickets for the 2018 gala were $30,000 each and tables were $275,000. Wintour will invite up-and-coming designers to the event, who don't have to pay. In other cases, a brand will pay for a table and invite celebrities to sit at its table. No matter who is invited, Wintour reportedly approves them personally.

Following the theme

It's not explicitly said that guests should follow the theme, but it's encouraged. Some themes, such as 2015's "China Through the Looking Glass," led to some culturally incorrect clothing. At that year's gala, Lady Gaga wore a kimono-style Balenciaga dress, but kimonos are traditional Japanese garments. And however unintentional, multiple people played on the Dragon Lady stereotype -- Justin Bieber wore a gold dragon-embroidered black velvet jacket by Balmain and Jennifer Lopez wore a Versace illusion gown with a red ruby dragon.

Other themes are more challenging to follow, among the most notable being the 2017 theme, "Rei Kawakubo/Comme des Garçons: Art of the In-Between." That year, the gala celebrated Japanese designer Rei Kawakubo. Although Rihanna wore a piece from the designer herself, others interpreted the theme through new pieces, and others wore more traditional, typically elegant red carpet attire.

Public red carpet, private party

Although the main event at the Met Gala is seeing whose designs guests are wearing and how they interpret the theme on the red carpet, the main event -- the dinner -- is private. Cameras are rarely allowed inside. After the red carpet, social media posts are banned, but celebrities have increasingly shared snaps inside the party and in bathrooms during smoke breaks -- the latter of which has reportedly since been banned.