Taylor also released a music video for the song, containing behind-the-scenes footage and more.

In a series of tweets, she announced: "cardigan "cabin in candlelight" version is out now ... The video for cardigan "cabin in candlelight" version is out now using new behind-the-scenes footage from the album photoshoot."

Taylor revealed this week that she did her own makeup, hair and styling for the promo.

Sharing a picture from the video, she wrote: "A million thank you's to my brilliant, bad ass video team - cinematographer Rodrigo Prieto, producer Jil Hardin, executive producer Rebecca Skinner, AD Joe 'Oz' Osbourne, editor Chancler Haynes, special effects wizards David Lebensfeld & Grant Miller, and set designer Ethan Tobman. The entire shoot was overseen by a medical inspector, everyone wore masks, stayed away from each other, and I even did my own hair, makeup, and styling (sic)"

Taylor announced the surprise album last week, and didn't tell her label or friends until the very last minute.

The 30-year-old singer wrote on Twitter at the time: "Tonight at midnight I'll be releasing my 8th studio album, folklore; an entire brand new album of songs I've poured all of my whims, dreams, fears, and musings into. Pre-order at https://store.taylorswift.com ... folklore will have 16 songs on the standard edition, but the physical deluxe editions will include a bonus track "the lakes." Because this is my 8th studio album, I made 8 deluxe CDs & 8 deluxe vinyls available for 1 week [smiley emoji] Each has unique covers & photos https://store.taylorswift.com (sic)"

Taylor explained via Instagram that she hadn't actually planned to release her new album at this time.

But recent events have reminded her that "nothing is guaranteed" in life.

She wrote on the photo-sharing platform: "Before this year I probably would've overthought when to release this music at the 'perfect' time, but the times we're living in keep reminding me that nothing is guaranteed. My gut is telling me that if you make something you love, you should just put it out into the world. That's the side of uncertainty I can get on board with. Love you guys so much [love heart emoji] (sic)"