Taylor Swift surprised fans with her new record "The Tortured Poets Department" on Friday, revealing it was a double album featuring songs about heartbreak and a period described as "the saddest story" of the singer's life.

Swift's 11th studio album, featuring 16 tracks, was officially released at midnight ET (O400 GMT), but two hours later she revealed a second installment with an extra 15 songs.

"I'd written so much tortured poetry in the past 2 years and wanted to share it all with you," Swift wrote on Instagram.

"Poets" comes 18 months after 2022's "Midnights". Swift will also release a video for the new album's first single, a collaboration with Post Malone called "Fortnight", on Friday.

The 34-year-old has been crossing music industry milestones and boosting local economies with her record-breaking Eras Tour, which resumes in Paris in May.

Time magazine named Swift its 2023 Person of the Year, citing her musical accomplishments and influence on everything from pop culture to voter registration.

A description of "Poets" in a separate Instagram post said it was "an anthology of new works that reflect events, opinions and sentiments from a fleeting and fatalistic moment in time - one that was both sensational and sorrowful in equal measure".

"This period of the author's life is now over, the chapter closed and boarded up," it added.

"There is nothing to avenge, no scores to settle once wounds have healed. And upon further reflection, a good number of them turned out to be self-inflicted."

The Instagram post did not say which events Swift was referring to. Fans have speculated she was writing about her relationship with British actor Joe Alwyn. The pair split in April 2023 after six years of dating.

A representative for Alwyn could not immediately be reached for comment.

Reviews were mostly positive, with Rolling Stone calling the music "wildly ambitious and gloriously chaotic", but others were not as impressed. Britain's NME described it as "surprisingly flat and, at times, cringeworthy".

"The Tortured Poets Department is extreme in its emotions and uninterested in traditional hits; not everyone will love it, but the ones who get it will adore it fiercely," Billboard said.

Swift stoked excitement earlier in the week by releasing clues such as a word of the day on Apple Music and snippets of lyrics at a library built at a Los Angeles shopping mall.

Fans dissected each tidbit, even noting that avowed cat lover Swift chose to release the album on National Cat Lady Day.

Swift announced "Poets" in February on stage at the Grammys, where she won a fourth album of the year prize for "Midnights". (Reporting by Lisa Richwine; additional reporting by Marie-Louise Gumuchian; editing by Alexander Smith and Jan Harvey)