The e-book revolution really began in November 2007, when Amazon.com released the first Kindle e-reader.

The device, which met with moderate success, provided wireless download capabilities over Amazon Whispernet. Accessible without any fees, Whispernet allowed users to easily browse, purchase and instantly download books.

Perhaps the most drool-worthy feature of the Kindle was its innovative E Ink electronic paper display. Intended to mimic real ink and paper, the gray screen with black text displayed ink particles electronically.

Because the display was not backlit, the screen reflected light like actual paper, eliminating glare and eyestrain and allowing users to read in bright light.

The transition from paper reading to electronic reading took some adjustment, but readers soon adapted and championed the e-paper display.

The Kindle 2, which went on the market in February 2009, boasts major improvements over its predecessor.

In addition to its sleek, sexy new look, Kindle 2 has better screen resolution, faster page turns, text-to-speech capabilities and seven times the memory. While the original Kindle could only support Microsoft Word files, Kindle 2 supports numerous file types, including PDF, HTML, MOBI, JPEG, GIF, and PRC.

The most lauded feature is Whispersync, which lets users synchronize data (for example, the last page read) across Kindles and other mobile devices. Amazon also launched an iPhone application — available at the App Store — which allows Kindle content to be read on the iPhone and iPod touch.

Just a few months after the release of the Kindle 2 came the larger, pricier Kindle DX.

The screen on this deluxe model is 2.5 times larger than previous Kindle screens and marketed as more suitable for displaying newspaper and textbook content. The DX adds a native PDF reader, the auto-rotating screen Apple fans love, stereo speakers, and a wireless fallback option for when Whispernet connectivity is unavailable.

Since its debut, Kindle has competed with other e-paper devices, including the Bookeen CyBook, Cool-ER, iRex iLiad, and Jinke Hanlin e-Reader.

The strongest competitor so far has been the Sony Reader, in its various incarnations. The latest version, the Sony Reader PRS 700BC, is often envied by Kindle users for its touch-screen interface and optional memory card (a feature included in Kindle 1 but absent from Kindle 2 and DX).

Kindle 3 is slated for release in early 2010 and will face stiffening competition from companies introducing their first e-readers to the market.

 Apple, Plastic Logic (a start-up company spun off from Cambridge University's Cavendish Laboratory) and FirstPaper (backed by the publisher Hearst Corp.) are expected to roll out portable reading devices in 2010. Plastic Logic's e-reader is already being referred to as the "Kindle Killer."

Tomorrow: Books vs. e-books