NAHANT – When Julie Johnson published her first book, “Like Gravity,” in 2013, she thought it might sell a hundred or so copies among friends and family members. The lifelong bookworm thought self-publishing could be a fun experiment.The last thing the Nahant native expected was for “Like Gravity” to sell more than 10,000 copies and hit a Kindle top sellers list, allowing her to become a full-time author and pay off her college debt.Today, the 23-year-old Johnson is the author of three self-published, young-adult fiction novels, which have all sold more than 10,000 copies each.?The average self-published book sells a few hundred copies,” she said. “I?ve been very lucky.”Johnson, a Nahant resident whose full legal name is Julie Johnson Liscio, has always been a reader. As a kid, she would spend afternoons at the library, digesting everything from young-adult fiction to sci-fi.But it wasn?t until her junior year at the University of Delaware that she decided to try writing novels.?I kind of just was inspired by all of the books that I read. There were so many self-published authors I liked, and I thought, ?look at all these women who are self-publishing. Why not try writing (a book)??” she said. “It was a spur of the moment thing. It kind of grew into a hobby, and then an obsession.”Her three current books, “Like Gravity,” “Say the Word” and “Erasing Faith,” are geared towards young adults. But Johnson said she?s not married to the genre.?I love to read all genres, so I can?t imagine why I wouldn?t write all genres,” she said.Johnson has found her success in self-publishing, which gives her the freedom to write what she wants. She has been approached by publishing houses about book deals, and has even discussed movie rights to her work. But while she is interested in eventually signing with a publishing house, she said she?s in no rush.According to July 2014 data from Author Earnings, a research project that analyzes Amazon, 25 percent of e-books on Amazon?s bestseller list were independently published. The data also said 45 percent of books came from a small or medium publisher, and just 16 percent came from the big five publishing companies.?It used to be publishing houses were gatekeepers. Now anybody can publish,” Johnson said. “You really have to make sure you market your book right, make those connections, make sure it gets in front of the right people.”One of those people was Aestas, a book blogger with about 44,000 Facebook followers. This past summer, Aestas reviewed “Say the Word” and gave it 4? out of 5 stars. Getting that kind of recognition boosted her visibility, Johnson said.Besides blog endorsements, one of the other things Johnson said she likes about being a 21st century author is the instant access she has to her readers. She keeps Facebook, Twitter and Goodreads profiles, where she?s able to talk to fans around the world.Her best friend, Blyss Galizia, a nurse and fellow Delaware alum, said the first time Johnson sent her a PDF of a novel, she walked around her apartment all day with her laptop in hand because she couldn?t put it down.Galizia said she was blown away by her friend?s ability to keep her own voice consistent throughout the novel.?I felt like her and I were having a conversation, or laughing about different people we had known in college,” she said. “I felt like I was talking to my friend.”