To some, watching television as a source of entertainment rots the brain and idles one's intelligence.

But besides being an entertainment medium, it is a very popular tool among English-language learners, according to studies.

Eighty-two percent of English learners polled by Kaplan International Colleges in 2012 said watching television helped them acquire the language.

Twenty-six percent of the participants said the popular situation comedy (or sitcom), Friends, helped them the most of any series in understanding the language.

Friends is a series about a group of attractive young Americans at home, at work and hanging out at their favorite coffee shop, Central Perk. ("Perk" is a nickname for percolating or brewing coffee. The coffee shop is near New York City's famed Central Park.)

In another study, almost 58 percent of English learners surveyed in 2015 by Pearson English, an education publisher, reported that they used movies and TV shows to help them. In that survey, 24 percent said the Netflix series House of Cards, a political drama about a U.S. congressman who stops at nothing to become president, helped improve their English skills the most.

Walter White, played by Bryan Cranston, and his wi FILE - Walter White, played by Bryan Cranston, and his wife Skyler White, played by Anna Gunn, during the first season of "Breaking Bad." FILE - Walter White, played by Bryan Cranston, and his wife Skyler White, played by Anna Gunn, during the first season of "Breaking Bad."

Learning English by watching programs with English subtitles is another favorite of language learners. Sixty Spanish students who watched an episode of Downton Abbey — a popular historical drama set on a massive estate in the English countryside — learned more English by watching with English subtitles than without, according to a study published in scientific journal PLOS One in 2016.

English is the most studied language in 116 countries, according to Duolingo, a language-learning app. The app is used in more than 300,000 classrooms, according to spokesperson Michaela Kron in Pittsburgh.

Other television programs that helped non-native English speakers learn the language included The Simpsons, an animated comedy, How I Met Your Mother, about a group of friends in New York City looking back on their lives, and Breaking Bad, about a teacher turned methamphetamine dealer in New Mexico.

In the Kaplan study, many of those who found Friends helpful in their study of English said they were more likely to want to travel to the United States to continue learning the language.

Anne-Caroline Verret started watching American programming in the fifth grade at home in Haiti.

"I would mostly watch the Disney Channel like every Saturday, like the Mickey Mouse Clubhouse, and I would always have the subtitles," said Verret. "So around fifth grade is when I really started picking it up."

Verret came to the U.S. after an earthquake in 2010 devastated her country. Understanding English made the transition easier for her.

"Honestly, I feel like it helped me a great, like, greatly because I came to the U.S. a year later due to the earthquake," she said. "I was in sixth grade, and I fully understood my teachers. I fully understood when what people were speaking to me. I could answer, I had a little accent, you know, obviously, but still, I was very surprised at how much I picked up."

While she had English lessons at school, Verret said she found that watching television and reading books helped her more. She continued to pick up on the language in school in the U.S.

While the U.S. does not have an official language, English is the primary language in the country and in more than 50 countries, reports the CIA World Factbook.

Also, U.S. employers can legally require their employees to speak English.