Brat Summer is a fashion and lifestyle microtrend that originated in mid-2024, directly inspired by the release of British singer Charli XCX's sixth studio album, Brat . The aesthetic is defined by a specific visual style—most notably the album's signature lime green color and low-resolution font—and a cultural attitude of confident, chaotic, and unapologetic hedonism.

The trend is a fusion of Indie Sleaze and Y2K fashion, celebrating a "messy, imperfect self-acceptance." As defined by Charli XCX herself, the "Brat" persona is "a bit messy and loves to party," and is "honest, blunt and a little bit volatile."

The Brat Summer phenomenon was sparked by the highly effective and viral marketing campaign for Charli XCX's album, Brat . The album's minimalist yet instantly recognizable cover art (the word "brat" in a simple, low-resolution font against a jarring lime-green background) became a easily replicable meme. The label created a "Brat Generator" website, allowing users to create their own versions of the cover, which quickly saturated social media.

The trend exploded beyond the music world when it was unexpectedly adopted by the Kamala Harris presidential campaign in July 2024. After Charli XCX tweeted "kamala IS brat," the campaign's social media accounts rebranded their banners with the signature "brat green" and font, turning the aesthetic into a mainstream political and cultural talking point. The phenomenon was so significant that Collins Dictionary named "brat" its 2024 Word of the Year.

The Brat Summer aesthetic is a rejection of the polished " clean girl " look in favor of a more raw, grungy, and party-centric style. The most defining visual element is the color "brat green," a specific shade of acidic lime green that became the official color of the season. The fashion itself is a mix of Y2K and Indie Sleaze staples. It is characterized by strappy white tops (often worn without a bra), miniskirts, low-rise jeans, and grungy streetwear. The overall look is intentionally "trashy" and effortless. The beauty look complements this with smudged eyeliner and a generally less-is-more approach that embraces the appearance of having partied all night.

Brat Summer is defined by a specific attitude. It is a celebration of confident and independent femininity. As described by Lena Dunham, "Brat is walking down the street with headphones on and eyes closed, knocking over passersby and refusing to say you’re sorry." The ethos encourages a form of "female rage dressed in green," challenging conventions and embracing a messy, unapologetic approach to life.