The e-book choice — rent, borrow, or buy?

Shopping for electronic books is simple. Too simple. Most of us just visit an online retailer, like Amazon or Apple or Barnes & Noble, and stock up on digital literature. It's painless — cheaper than a trip to a brick-and-mortar store, and much too limited.

Compare that to the online movie business. You can buy a digital copy of the film, but you can also rent it for a day or two, or get a $7.99 monthly subscription to Netflix and stream it over the Internet whenever you like.

Each option is just right for a particular sort of film buff. E-books already hold 30 percent of the US book market. But they will do even better as companies give us more ways to read them.

Serious e-book fans probably know about OverDrive, an attractive but limited service that lets you borrow electronic books from a local library free of charge. Now a pair of companies, Oyster and Scribd, have launched all-you-can-read services based on a Netflix-like subscription model.

And another new company with a dreadful name, eReatah, is positioning itself as the digital successor of the classic Book of the Month Club.

OverDrive Inc. was early to the party. It has been distributing e-books to public libraries since 2001 and now provides 1.8 million downloadable e-books and audiobooks to about 90 percent of public libraries nationwide, including Boston's.

The company makes apps that run on pretty much everything — personal computers, Apple Inc.'s iOS, Android, Windows Phone and BlackBerry devices, even Amazon.com's Kindle e-book readers.

Just install the software and punch in the digital ID code on your library card. That allows access to whatever titles the library has chosen to stock. Once you have the book or audio recording, you can use it for a limited time — 14 days, for example. After that, the file is locked and unreadable unless it's checked out again.

But libraries must pay a separate license fee for each OverDrive digital book they lend. So if a library's 10 digital copies of the latest Dan Brown novel are all "checked out," you'll join a waiting list.

The new e-book rental services suffer from no such limits. With Oyster, for instance, it costs $9.95 a month to read any title in its electronic library. You won’t run out of reading anytime soon; Oyster offers 100,000 titles, with more to come. And these aren’t the usual out-of-copyright 19th-century novels found for free online at places like Project Gutenberg or Archive.org. Oyster carries recent bestsellers by major authors — not the latest, newest stuff, but pretty close. Last year’s Mark Helprin novel, “In Sunlight and In Shadow,” pops up. So does this year’s excellent technology book “Big Data.”

For some reason, Oyster is currently accessible only via an iPhone, iPad, or iPod Touch. There's no support for devices running Google Inc.'s Android software, or even for personal computers.

Oyster's rival Scribd works in much the same way as does Oyster. Scribd does not reveal how many titles it offers, though the website inventory has a lot in common with Oyster's. But Scribd undercuts Oyster on price, charging $8.99 a month. And Scribd books are accessible through any standard Internet browser, so they can be read on a laptop or desktop PC, tablet, or smartphone. Also, there are apps for Apple and Android devices that let you download entire books to read offline.

EReatah, which is scheduled to be launched around Thanksgiving, features a starkly different business model. A subscriber can download two electronic books per month, using apps for Apple iOS or Android devices, for $14.99 a month. It costs more to read more: A four-book subscription costs $29.99 a month.

Generally, books from eReatah cost less than they would at standard online booksellers. And you are buying them, not borrowing. Cancel your subscription and you keep every eReatah book you downloaded.

EReatah claims a library of about 100,000. These include the entire catalogs of many publishers, the biggest being Simon & Schuster. It even offers some current bestsellers, like Stephen King's "Doctor Sleep."

I buy a lot of my e-books on impulse — a single, simple click of the mouse at Amazon.com. But with so many attractive options springing up, e-book shopping just became a lot more complicated, in a good way.