Photo When using the iPad's web browser to shop for books in Amazon's Kindle Store, click the Buy button and the book will open in the Kindle reading app. Credit The New York Times

Q. I have many books on my Kindle. How can I get them onto my iPad? And why does my Kindle app on the iPad not let me buy a book with that device?

A. If you have already downloaded the Kindle app for iPad, log into it with the same Amazon account user name and password you use to buy the books on your Kindle e-reader. Once you have logged in on the iPad, you should see all the Kindle books you have bought shown on the Cloud tab at the bottom of the All Items screen. Tap a book cover to download the title from Amazon's Cloud to your iPad's Kindle library. To see the books that have been downloaded to the iPad, tap the Device tab at the bottom of the All Items screen.

Apple's rules for developers and companies selling software in its App Store require that everyone use its In-App Purchase system to sell digital goods. However, Apple takes a 30 percent cut of the In-App Purchase price, which has caused many companies (including Amazon) to go outside Apple's App Store to sell additional content for their iOS apps.

While the Kindle app for iPad may lack a Buy button for directly purchasing books on the tablet, Amazon suggests an alternate approach that uses the iPad's Safari browser. Open Safari and enter www.amazon.com/ipadkindlestore in the address bar. Log into your Amazon account on the page and then tap the Share button on the right side of the address bar. Select Add to Home Screen to create a bookmark for the Kindle Store. Use this icon for book shopping. To buy a book, tap the Buy button and then the Read Now button on the page to automatically download the book and open it in the iPad Kindle app.

When you buy books on Amazon's website on the computer, you can have them delivered to the iPad. Just log into the Manage Your Content and Device page at https://www.amazon.com/mycd, enter your password and select the book you want to push to the iPad. Click the Deliver link, select the iPad from the device list and hit the Deliver button.