Are iPads sending people to their local public library? Sunnyvale official Lisa Rosenblum thinks so.

Just last week, Rosenblum said, she was approached at the city library by a middle-aged resident who admitted he hadn't visited there for years. The man was applying for a library card because he'd bought a new iPad and wanted to borrow electronic books.

"The iPad, the Kindle, all these mobile devices are becoming more affordable and people are discovering what they can do," said Rosenblum, who is Sunnyvale's director of library and community services. "But then they realize they have to pay for downloads" from commercial sites, "and when they find out the library can provide them at no charge, they're coming back in."

While they don't see themselves competing with Amazon, Apple or Google, public libraries around the Bay Area are expanding their lists of ebook titles, which local residents can borrow and read for free.

Many library books still aren't available in electronic form: Librarians say publishers refuse to make some titles available, or set prohibitive terms for libraries -- such as fees that are three or four times the retail price of an ebook, or limits on how often a book can be loaned out -- for fear that free downloads will cut into their sales. And in some cases, library patrons face a confusing array of ebook lending platforms and formats.

But those platforms are getting simpler and more standardized, making it easier for users to borrow ebooks from major publishers as well as small independents, and read them on a variety of electronic devices.

"It's changing; they're getting better and better," said Jamie Turbak, acting associate director for the Oakland Public Library, who said a small but growing number of her patrons are particularly drawn to science fiction, best-sellers and children's books in digital format.

San Jose readers go for digital fiction of all kinds, and travel books in summer, said Katie DuPraw, a division manager for the San Jose Public Library, which boasts 80,000 ebook titles. "People like to download travel books just before they go on vacation," she said. "It's lighter than carrying printed books in your suitcase."

While some research indicates that people are reading fewer printed books, more people are reading in digital format. Surveys by the Pew Research Center found 28 percent of Americans read at least one ebook in 2013, up from 16 percent in 2011. The numbers are higher for young people: Pew found 47 percent of those age 18 to 29 read an ebook last year.

"It's our responsibility to be in tune with our customers: They are reading online, and we know that," said Cathy Sanford, deputy librarian for Contra Costa County, which has about 50,000 ebook titles.

Romance and erotica are among the popular categories, Sanford said. Some readers may be more comfortable downloading those titles at home, she explained, rather than physically carry a book to their library checkout counter.

Still, she acknowledged, many people still tell her "they didn't know you could borrow ebooks from the library."

The process can seem daunting. In order to provide a range of titles, most libraries work with multiple distribution companies, which act as middlemen for the publishers and provide the software that allows library users to find and download books.

Some distributors require users to download a separate app so books can be read on a particular device, such as an iPad, Android tablet or e-reader. Some also require users to create a free account with Adobe, whose software prevents unauthorized copying.

But distributors and libraries have worked to simplify their systems: Instead of separate websites for each distributor, many users can now visit their own library's online catalog to search for an author or title. If a book is available electronically, users can type in their library card number and, with several clicks, download the text in a format that works for their device.

Digital borrowers don't have to worry about returning overdue books: Most can be renewed in advance, but they automatically delete from the borrower's device when the loan period ends.

Depending on the distributor, some library ebooks can't be downloaded to the popular Kindle e-reader from Amazon, which competes with libraries as a seller of books. But at least one leading distributor, Ohio-based OverDrive, has struck a deal with Amazon that allows borrowers to read on Kindles.

While OverDrive has relationships with the nation's biggest publishers, some libraries have chafed at its licensing restrictions. Last year, the Contra Costa County system joined with a statewide library group to create their own service called enki, which distributes ebooks from independent publishers and self-publishing houses like Los Gatos-based Smashwords.

"Their material is every bit as good as the big publishers, and they're looking for new ways to get their titles out," Sanford said. Most local libraries now offer enki books.

Despite the popularity of digital books, not all readers own electronic devices. Some libraries, including Sunnyvale's, have purchased e-readers that patrons can borrow.

Libraries also say their staffers are happy to advise patrons on how to download ebooks. "The questions always spike around the holidays," when people get new gadgets as gifts, said San Jose's DuPraw.

Contact Brandon Bailey at 408-920-5022; follow him at Twitter.com/BrandonBailey