"Ribs" was written by Lorde — credited under her birth-name Ella Yelich-O'Connor — and Joel Little who also handled production, engineering, instrumentation and mixing.

[11] "Ribs" is a deep house-influenced electronica, indietronica, and electropop song,[4][6] which starts ambiently and,[5] according to Jason Lipshutz of Billboard, features an "exhausted-sounding Lorde growing more frantic with each passing second," with lyrics that include the singer discovering her maturity and "grown-up problems."

[12] Consequence of Sound noted how Lorde's minimal production allowed her to sing in any melody, layering them over one another to create a choral effect.

[15] On 24 September 2013, she performed the track at The Fonda Theatre in Los Angeles, California,[16] and at a concert at the Warsaw in Brooklyn on 3 October 2013 along with other material from her album Pure Heroine.

[17] On 26 November 2013, Lorde performed the song on the Late Show with David Letterman, backed by a drummer and a keyboard player.

While the publication praised its "dark and cold" chorus, it was also critical of the "same stacked vocals, hypnotic percussion, and synthesized production" that made the track repetitive.

Club called "Ribs" the "best illustration of [Lorde's] gift,"[26] while Jon Hadusek of Consequence of Sound placed it as one of the album's essential tracks in his review.