We pre-emptively apologize for getting it stuck in your head.

But “Baby Shark,” a song as infectious as anthrax to which the caretakers of young children likely need no introduction, entered the Billboard Hot 100 chart at No. 32 this week, placing Pinkfong, a South Korean educational brand, alongside the world’s top musical artists.

“Baby Shark,” which Pinkfong says it based on a “traditional singalong chant,” has been viewed more than 2.1 billion times on YouTube, making it among the 30 most-viewed videos ever.

It was streamed 20.8 million times just in the past week, Billboard said, with 73 percent of those streams coming from video.

Its rise onto the charts comes long after SmartStudy, a Seoul-based company that has produced thousands of children’s videos under the Pinkfong brand, first posted it on YouTube in November 2015. The company remixed it, adding a new beat and melody, in the now-popular version posted in June 2016. It has now been adapted into more than 100 versions in 11 languages, the company said.

The song was helped along by attention from K-pop acts in Korea and spread throughout Southeast Asia before eventually finding its way to the United States in 2018, when a social media challenge invited people to post videos of themselves dancing to the song. Participants included Ellen DeGeneres and James Corden, while Kylie Jenner and Cardi B made references.

It first appeared on Billboard’s Kid Digital Song Sales chart in July, followed by the Streaming Songs chart in November. It also made it to the U.K. Top 40, which is not produced by Billboard, in September.

Making a Top 40 list is far from easy. Jimi Hendrix made it to Billboard’s just once. Wu-Tang Clan never made it.

But today’s charts are different, and often include an eclectic mix of music. Billboard has made a series of changes to its rankings for an era in which viral hits on social media can capture more attention than sustained radio airplay, and consumers download more music than they buy in record shops.

In 2012, Billboard began counting digital sales and online streams in its singles chart, immediately lifting “Gangnam Style,” the YouTube hit by South Korean rapper Psy, to the top of the new Rap Songs chart.

In 2014, Billboard and Nielsen SoundScan, the agency that supplies Billboard’s data, added streams and downloads to its album chart formula. Billboard and Nielsen tweaked the formula in July, making streams from paid services like Spotify and Apple Music worth about three times as much as those from “free” users, including YouTube viewers.

Bin Jeong, chief executive of Pinkfong USA, said in an emailed statement that the digital content company is responding to the success of “Baby Shark” by creating toys, DVDs and other consumer products, including books and diapers. The company, which has about 200 employees in offices in South Korea, the United States and China, is also working on TV shorts and a movie, he said.

“We are not planning to settle for Baby Shark hitting the music charts and getting YouTube views, but we are developing Pinkfong and Baby Shark into an entertainment brand that will be enjoyed by generations to come,” she said.