The Copia e-reader hits Windows 7 tablets.

LAS VEGAS--Part online bookstore, part e-reader, and part social network, Copia has just added Windows 7 tablets to its lineup of supported devices.

Being demonstrated this week at CES, Copia for Windows 7 tablets uses the same reading and social-networking environment found on other devices and platforms. The Copia app makes its Windows 7 tablet CES debut on such systems as the new Samsung Sliding PC 7, also on display at CES.

So how does Copia work

You can buy digital books directly from Copia's online bookstore and load them on any supported device. The e-reader app itself is free, with most versions available for download from the company's Web site.

Reading an e-book through Copia is similar to reading one on most other e-readers, except there's a social aspect. Your Copia library list is shareable, should you choose to share it. So when you add a new book to your library, other people can see the books you're reading.

You can share your library list with everyone in the Copia community or just with friends that you've added to your own network. You can even create Copia discussion groups centered on different books or topics and make those groups either private, open by request, or open to everyone.

Copia also taps into connections to Facebook and Twitter, so you can invite your friends from other networks to join you on Copia.

You can view the books in your library in list view, grid view, or in a tag cloud view that changes the size of the book's image depending on how much interest and buzz the book has received from other readers. The more comments, discussions, and reviews about the book, the larger it appears. You can also tap on any book to read what the Copia community is saying about it and even filter comments and reviews to see those just from your friends.

As you read the book, you can highlight passages, write notes, and make comments. If you so choose, your notes and comments can then appear in the same e-books owned by your friends and people in your discussion groups. This way, you can trigger a back-and-forth conversation about specific passages in a book among your fellow Copia users. Notes and comments can be organized into separate notebooks, so you can review all the ones you've made. Tapping on a specific note opens up the associated passage in the book itself.

Beyond Windows 7 for tablets, Copia runs on PCs and Macs, the iPhone and iPad, Android devices, and Windows Phone 7, among other environments.