Any device that can display text on a screen may act as an e-reader, but specialized e-reader devices may optimize portability, readability (especially in sunlight), and battery life for this purpose. Their main advantage over printed books is portability: an e-reader is capable of holding thousands of books while weighing less than one and the convenience provided due to add on features in these devices.
An e-reader is similar in form factor to a tablet computer. E-readers are a convenient way to read e-books since the battery can last for several weeks, compared to a laptop that usually needs daily battery charging; in addition an e-reader does not have apps that may distract its user from reading.
The Sony Librie, released in 2004 and the precursor to the Sony Reader, was the first e-reader to use electronic paper. The Ectaco jetBook Color was the first color e-reader on the market, but its muted colors were criticized.
Many e-readers can use the internet through Wi-Fi and the built-in software can provide a link to a digital Open Publication Distribution System (OPDS) library or an e-book retailer, allowing the user to buy, borrow, and receive digital e-books. An e-reader may also download e-books from a computer or read them from a memory card. However, the use of memory cards is decreasing as most of the 2010s era e-readers lack a card slot.
There have been several generations of dedicated hardware e-readers. The Rocket eBook was the first commercial e-reader and several others were introduced around 1998, but did not gain widespread acceptance. The establishment of the E Ink Corporation in 1997 led to the development of electronic paper, a technology which allows a display screen to reflect light like ordinary paper without the need for a backlight; electronic paper was incorporated first into the Sony Librie that was released in 2004 and Sony Reader in 2006, followed by the Amazon Kindle, a device which, upon its release in 2007, sold out within five and a half hours. The Kindle includes access to the Kindle Store for e-book sales and delivery.
As of 2009[update], new marketing models for e-books were being developed and a new generation of reading hardware was produced. E-books (as opposed to e-readers) have yet to achieve global distribution. In the United States, as of September 2009, the Amazon Kindle model and Sony's PRS-500 were the dominant e-reading devices. By March 2010, some reported that the Barnes & Noble Nook may be selling more units than the Kindle in the US.
Research released in March 2011 indicated that e-books and e-readers are more popular with the older generation than the younger generation in the UK. The survey carried out by Silver Poll found that around 6% of people over 55 owned an e-reader, compared with just 5% of 18- to 24-year-olds. According to an IDC study from March 2011, sales for all e-readers worldwide rose to 12.8 million in 2010; 48% of them were Amazon Kindles, followed by Barnes & Noble Nooks, Pandigital, and Sony Readers (about 800,000 units for 2010).
On January 27, 2010 Apple Inc. launched a multi-function tablet computer called the iPad and announced agreements with five of the six largest publishers that would allow Apple to distribute e-books. The iPad includes a built-in app for e-book reading called iBooks and had the iBookstore for content sales and delivery. The iPad, the first commercially profitable tablet, was followed in 2011 by the release of the first Android-based tablets as well as LCD tablet versions of the Nook and Kindle; unlike previous dedicated e-readers, tablet computers are multi-function, utilize LCD touchscreen displays, and are more agnostic to e-book vendor apps, allowing for installation of muilple e-book reading apps. The growth in general-purpose tablet use allowed for further growth in popularity of e-books in the 2010s.
In 2012, there was a 26% decline in sales worldwide from a maximum of 23.2 million in 2011. The reason given for this "alarmingly precipitous decline" was the rise of more general purpose tablets that provide e-book reading apps along with many other abilities in a similar form factor. In 2013, ABI Research claimed that the decline in the e-reader market was due to the aging of the customer base. In 2014, the industry reported e-reader sales worldwide to be around 12 million, with only Amazon.com and Kobo Inc. distributing e-readers globally and various regional distribution by Barnes & Noble (US/UK), Tolino (Germany), Icarus (Netherlands), PocketBook International (Eastern Europe and Russia) and Onyx Boox (China). At the end of 2015, eMarketer estimates that there are 83.4 million e-reader users in the US, with the number predicted to grow by 3.5% in 2016. In 2014, the New York Times predicted that by 2018 e-books will make up over 50% of total consumer publishing revenue in the U.S. and UK.
Until late 2013, use of an e-reader was not allowed on airplanes during takeoff and landing. In November 2013, the FAA allowed use of e-readers on airplanes at all times if it is set to be in Airplane Mode, which means all radios turned off and Europe followed this guidance the next month.
Many of the major book retailers and third-party developers offer e-reader applications for desktops, tablets and mobile devices, to allow the reading of e-books and other documents independently of dedicated e-book devices. The e-reader applications are available for the Mac and PC computers as well as for Android, Blackberry, iPad, iPhone and Windows Phone devices. Examples are apps that run on these platforms that work like the Amazon Kindle, Barnes & Noble Nook and Kobo eReader.
An idea similar to that of an e-reader is described in a 1930 manifesto written by Bob Brown titled The Readies, which describes "a simple reading machine which I can carry or move around, attach to any old electric light plug and read hundred-thousand-word novels in 10 minutes". His hypothetical machine would use a microfilm-style ribbon of miniaturized text which could be scrolled past a magnifying glass, and would allow the reader to adjust the type size. He envisioned that eventually words could be "recorded directly on the palpitating ether".
Public domain books are those whose copyrights have expired, meaning they can be copied, edited, and sold freely without restrictions. Many of them can be downloaded for free from websites like the Internet Archive in formats many E-readers support, like PDF, TXT, and EPUB. Books in other formats may be converted to an e-reader compatible format using Calibre.
The introduction of e-readers brought substantial changes to the publishing industry, also awakening fears and predictions about the possible disappearance of books and print periodicals.