E-books are becoming more and more popular.  The Association of American Publishers revealed this month that e-books have seen enormous sustained growth, while paper books have declined in all categories.  E-books are cheaper than going to a bookstore and buying a hardback or paperback, but just as portable and readable anywhere. They are also downloadable on demand, so if you can’t sleep and want to read at two o’clock in the morning, you can find a new book quickly and easily.  I'm an uber geek, and I've been reading e-books since 2001.  I've found that they don't completely replace the beauty and simplicity of paper books, but their easy accessibility, searchability, and price ultimately outweigh the cons.

The three most popular e-readers are the Nook, Kindle, and iPad.  Below is a look at the differences between these devices.

The Kindle

Amazon’s Kindle e-reader is low cost, lightweight, and has a nice e-ink screen. You can also read PDF files. It comes with Wi-Fi and a free 3G network.  There is also a Wi-Fi only version.

My biggest complaint about the Kindle is its tiny keyboard.  I like to take notes when I'm reading, and typing on a small keyboard is not natural and a bit awkward.  This, of course, is an issue with almost any e-reader when compared to taking notes with a pen or pencil on a paper book.  The Kindle, though, has the least natural keyboard of all of the eReaders that I've tested.

The greatest thing about the Kindle is the hundreds of thousands of e-books, newspapers, magazines, and blogs available for purchase and download.  The Kindle can hold 3500 books. The Kindle also offers several different fonts in different sizes, has a long battery life and you can play MP3s.  Amazon also offers a Kindle app for Mac, PC, iPhone, iPad, and Android devices that sync all of your books.

The Nook

The Nook is an e-reader from Barnes and Noble. It is an open e-book format (EPUB), which means that you can purchase books from a variety of places including Google Books.  Like Amazon, Barnes & Noble provides a Nook app so you can read and sync your e-books on other devices like the iPad, iPhone, or Android devices.

The Nook has a black and white e-ink display and a color touchscreen that you can use to turn the pages, buy books, and take notes on the virtual keyboard. It is light and holds up to 1500 books, although the memory can be expanded.

You can also connect to the Internet for free, and if you go into a Barnes & Noble store, you can get unlimited Wi-Fi access. The battery generally lasts 10 days and recharges in less than 4 hours.

The Nook Color is new to the e-reader market and is more comparable to a tablet, like an iPad.  It doesn't have an e-ink screen, but has many of the features you would expect from a standard e-reader.  Just yesterday, Barnes & Noble added apps to the Nook, which makes it even more closely aligned with a tablet device.

The iPad

The iPad has several functions, so it’s not just an e-reader.   Being a multi-functional device has its pros, but if you're looking for the best e-reader you'll have to weigh it's cons.  Namely, it doesn't have an e-ink display.  If reading from a backlit display doesn't bother your eyes (like an iPhone or computer monitor), the iPad is by far the best e-reader.

It is lightweight when compared with other tablets, but noticeably heavier than the Kindle.  It has a beautiful screen and long battery life. There are over 170,000 apps and you can play games and videos.

As an e-book reader, it is easy to use, and the font, text size and contrast can be customized to reduce eyestrain (as in all e-readers). One of the most valuable features is the variety of e-book stores you can choose from.  Apple has it's own store, called iBooks, which has a beautiful interface, but not as big of a book selection as Kindle, and sometimes the price of e-books is higher than on Kindle or Nook.  You can also get the Kindle and Nook apps, along with other e-reader apps, so you're not limited to any particular store.

When you’re considering which e-reader to purchase, there are several things to take into account:

• What size of screen do you want
• Whether you want Wi-Fi or 3G (which increases the price)
• What functions you desire besides reading
• Price (Starting prices:  Kindle- $139, Nook- $149, iPad- $499)
• Weight

Every e-reader has different functions, capabilities, and features, so personal preference is key. These are the three most popular e-readers on the market right now, although Kobo and Sony also have models available that you may want to check out as well.

Do you read e-books?  If so, why or why not?  If you do read e-books, what e-reader do you use?  We'd love to hear from you!