Amazon on Thursday introduced Windows PC software for reading e-books and synchronizing them with the Kindle e-book device.

The announcement came a couple of days after Barnes & Noble unveiled its competing Nook e-book reader, which has similar synchronization features. Both devices also sync with select smartphones, including the Apple iPhone.

Both the Kindle and Nook applications, which will be available at no charge, will make it possible for people to read part of a book on a PC or the e-reader and then pick up where they left off when they change devices. People without readers will be able to use the software to read e-books just on their PCs.

With the new Kindle application, people will be able to access previously purchased e-books from Amazon and view notes and highlights marked on the Kindle. Other features include the ability to choose from more than 10 font sizes, and zoom in and out of text with a pinch of the fingers, if the software is running on a Windows 7 PC with multi-touch capabilities. Future versions of the software will let people turn pages with the swipe of a finger.

The software runs on Windows XP and later versions.

Amazon plans to release its software for download next month. Barnes & Noble will start shipping the Nook at the end of November. The Nook will be priced at $259, which is the same as the starting price of the Kindle.

Amazon and B&N sell bestsellers for $10, as does rival Sony, which has its own reader and online store.

Electronic readers today are primarily used by avid readers and business travelers looking to lighten their load of books and magazines. Nevertheless, the market is growing. E-reader sales will reach 3 million units, with 30% of the purchases occurring during the holiday season, according to Forrester Research. Next year, sales could exceed 6 million units.

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