About How Long

"How Long" is a song recorded and produced by American singer Charlie Puth. He co-wrote the song with Jacob Kasher and DJ Frank E. It was released on October 5, 2017, by Atlantic Records as the second single from Puth's second studio album, Voicenotes (2018). Commercially, it has reached the top 10 in Belgium, Israel, Lebanon, Malaysia, the Philippines, Scotland, and the United Kingdom as well as the top 20 in Australia, Belgium, Denmark, Ireland, the Netherlands, New Zealand, Slovakia, Spain, and Switzerland. The song peaked at number 21 on the US Billboard Hot 100.

Puth teased the song in September 2017 on social media. He tweeted two photos in a row, which were captioned "how" and "long" respectively. In October 2017, he posted photos and video clips with the captions, "has", "this", "been" and "going". On October 4, 2017, he posted a video of the voice note recording behind the song with the caption "on", eventually spelling out "how long has this been going on" altogether, as one of the lines in the song's lyrics.