Media playback is unsupported on your device Media caption Sigrid gives us a tour of Bergen, where she lives in Norway

Norwegian pop singer Sigrid has won BBC Music's Sound of 2018, which aims to showcase the most exciting new music for the year ahead.

Aged just 21, she is one of the youngest ever artists to receive the honour - beaten only by Adele, who was 19 when she topped the 2008 list.

"It's a huge honour," she told the BBC. "I don't know how to explain it."

Influenced by Lorde, Robyn and Joni Mitchell, the star has become known for catchy, quirky and literate pop songs.

BBC Radio 1's Annie Mac called her "literally the perfect pop star" and "an absolute pleasure to play on the radio".

Media playback is unsupported on your device Media caption The moment Sigrid found out she'd won the BBC Music Sound Of 2018

The Sound of 2018 list was compiled using votes from 173 DJs, critics and festival bookers.

For the first time, this year's panel also included former nominees, including Stormzy, Ellie Goulding, Years & Years frontman Olly Alexander and last year's winner, Ray BLK.

The top five was a mixture of British and international, and unsigned and signed acts - all of whom were aged 22 or younger.

Emotive singer-songwriter Rex Orange County came second, while urban jazz act IAMDDB was third.

BBC Sound of 2018 - the top five

1) SIGRID

Media playback is unsupported on your device Media caption Sigrid performs Raw in Oygardshallen, Giske, Norway, close to where she grew up.

Taught to play piano at an early age, Sigrid didn't consider writing her own music until she was 16, when her brother demanded she stopped playing Adele covers. She quickly discovered a talent for indelible pop melodies, switching confidently between fragile ballads and feisty pop bangers.

2) REX ORANGE COUNTY

Media playback is unsupported on your device Media caption Rex Orange County: 'I chose it 'cos I like the name Rex'

Nineteen-year-old Alex O'Connor is a former chorister and Brit School graduate, whose bedroom productions were inspired by a love of classic songwriters like Stevie Wonder. His heartfelt vocals have been sought out by the likes of Tyler, The Creator and Skepta, who invited him on stage at last year's Mercury Prize.

3) IAMDDB

Media playback is unsupported on your device Media caption IAMDDB takes third place on the BBC Music Sound Of List 2018

Manchester's Diana DeBrito, aka IAMDDB, fuses reflective, soulful vocals with trap beats and jazz melodies. She dropped her first track just over a year ago, on the same day she quit university after just an hour.

4) KHALID

Media playback is unsupported on your device Media caption Khalid shares the secrets of his success

Aged just 19, Khalid is already a star in the US, where his debut album American Teen has sold more than a million copies. His emotional, relatable songs are a diary of his high school years, full of love, loss, loneliness and longing.

5) PALE WAVES

Media playback is unsupported on your device Media caption Get to know Pale Waves, who've taken fifth place in the Sound of 2018

Manchester goth-pop band Pale Waves were formed at university by best friends and musical soulmates Heather Baron-Gracie (vocals, guitars) and Ciara Doran (drums). Championed by The 1975, who took them on tour last year, they describe their sound as "90s-inspired indie-pop feels, drenched in reverb and glitter".

This year's winner was born Sigrid Solbakk Raabe in Alesund, a harbour town fringed by the mountains of western Norway.

The singer said she was amazed to be recognised by an international audience.

"I've always thought that, since I'm from a small country, it would be more difficult to get my music across. But I guess streaming opened a lot of boundaries."

She's also tweeted her reaction to winning, saying she was "speechless".

Sound of 2017 winner Ray BLK passed on her advice to this year's winner.

"Winning is just so overwhelming," she said. "Everyone's like, 'You're supposed to be the next Adele, the next Sam Smith', and it makes you think, 'Oh no! What do I do?'"

"But my advice would be: Just keep doing what you're doing. Build it your way."

Media playback is unsupported on your device Media caption Get to know the acts on the Sound of 2018 longlist

The Sound of... list launched in 2003 and has a track record in championing new and innovative acts, including 50 Cent, Haim, Frank Ocean, Ellie Goulding and Florence + The Machine.

According to the rules, acts on the longlist should not already be well known - so talent show contestants and members of famous bands launching solo careers are excluded.

Nominees could not have had a UK top 10 single or album - although guest vocalists remained eligible.

This year's longlist was dominated by pop acts, with Sigrid joined by fellow Scandipop artist Alma and dark pop practitioner Billie Eilish.

Other nominees included experimental eight-piece Superorganism, whose members hail from the UK, Japan, Australia and New Zealand; and Hackney-born rapper Not3s, who had a viral hit last year with his single Addison Lee (Peng Ting Called Madison).

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