My books say, 'by Ruby Barrett' but that's not my name. I use a pen name.
A pen name, or nom de plume, is a pseudonym and they've been used by authors for centuries for various reasons including hiding their gender (for example, Middlemarch by George Eliot is actually Middlemarch by Mary Ann Evans).
Sometimes authors use pen names because they write in different genres. It's a way for readers to distinguish between their works. J.K. Rowling is a famous example; she publishes her mystery series under Robert Galbraith.
Some romance authors specifically use pen names because they don't want people to know their real identities. I love the romance genre. It's empowering. It's sexy. It's fun to read and write. It is driven - in content and production - almost exclusively by women. But let's face the facts: people are still embarrassed by romance. So embarrassed in fact, that Real Simple actually published an article about 7 Romance Novels You Won't Feel Embarrassed About Reading (author Sarina Bowen wrote a fantastic rebuttal here).
And so some romance authors decide to use pen names to hide their identities because of the judgment they might experience because of the genre they choose to write in. I get it. I've experienced that same judgment. So some authors use a pen name to protect their identity and until the day everyone stops thinking romance is embarrassing, writers should continue to do so if they choose.
Say My Pen Name
My reason for using a pen name is less exciting. On the day I was born, my wonderful parents decided to give me a special name, a name that honoured my Scottish heritage, a Gaelic name.