"Fireflies" is the debut single from American electronica project Owl City's album Ocean Eyes.

"Fireflies" was Owl City's only top 40 hit on the Billboard Hot 100 until three years later when "Good Time", a duet with Canadian singer Carly Rae Jepsen, peaked at number eight on the chart.

According to Owl City's manager Steve Bursky, the song was not intended to be released as a single, however he stated, "it was an opportunity we couldn't pass up.

[9] "Fireflies" is centered on Young's struggle with insomnia; he first developed the song "awake in the early hours of the morning" to occupy his mind.

It was also inspired by a camping trip he took up to a "totally rustic and kind of remote lake in northern Minnesota"; he tried to emulate the experience of seeing a meteor shower that gave him "a cool idea of shooting stars being fireflies.

The song is layered with dozens of instrumental tracks, including its drum loop, piano, organ, synthesizer, vibraphone, violin, viola, and cello, which was performed by a cellist Young hired.

[11] The song features guest vocals from Matt Thiessen of Relient K, who Young had been a fan of since he was in high school.

"[16] In another positive review, Nick Levine of Digital Spy remarked, "there's nothing twee or cutesy about the socking great chorus Young unleashes here.

"[14] AltSounds stated that the song is, "simply built up with a calm, gentle automated vocal alongside some dreamy pimples of teen fantasy.

"[19] The song was widely compared to the music of synth-pop duo the Postal Service;[20][21][22] Young denied it was his goal to emulate their sound or vocalist Ben Gibbard.

[25] "Fireflies", when featured as iTunes' free "Single of the Week," garnered 650,000 downloads, influencing Universal Republic to move Ocean Eyes' release date from September 1, 2009, to July 28.

[31] "Fireflies" contributed to sales of the album Ocean Eyes, and was credited as being responsible for its entry to the top ten on the U.S.

1 in Denmark, Ireland, Sweden, Australia, the United Kingdom and the Netherlands (for 10 weeks) and the top ten in Austria, Belgium, Canada, Poland, Finland, Germany,[47] New Zealand, Norway, Portugal, and Switzerland.

[49][50] It features Adam Young playing the song on a Lowrey spinet organ in a toy-filled bedroom, where most of the toys (including Robie Sr.; a Tyrannosaurus rex; a Speak & Spell; toy cars, including one based on the UK children's TV character Brum; and a blimp) come to life.

Something about its mawkish, saccharine lyrics were so flawlessly inoffensive as to make it the perfect song for light-rock radio, and the track rippled through airwaves in malls, airports, commercials, and public transit until even the most earnest fans grew a little tired.

[55] The song received further notability in June when Owl City was asked to interpret the lyric "I get a thousand hugs from 10,000 lightning bugs.