Amazon's kindle hardware was first introduced in 2007 by Amazon followed by kindle DX that has a wider screen in the year 2009. The code name 'fiona' was originally used. Generally, the Kindle device is used solely for reading and therefore there is no access to other activities to avoid distractions when reading. Kindle apps has also been introduced to android phones, windows phone, blackberry 10 and also has a cloud reader to enable readers access e-books online. The newer models of kindle even offer WIFI connections. Older models came with card slots to enable the transfer of e-books to a memory card to create space for more e-books. The newer models no longer have card slots but have a high storage space. The Kindle also have different features like bookmarking a page, text selection and you can also take notes while reading. Amazon kindle is likely to take over hard-copy textbooks.
It also released a paperwhite and paperwhite 3G in 2012 that is similar to kindle touch. Batteries could also be replaced in older models which is no longer available in newer models. Newer models have a stronger battery and can last for about 2 months with WIFI turned off unlike older models that can only last for 2 weeks. The Kindle fire is the odd one that has only an 8-hour battery life. After users complained about using LCD screen which put a strain on their eyes after a while, Amazon introduced the 'Electronic ink'.
There are currently three models in sale currently: kindle, kindle oasis and kindle paperwhite. All kindles have back light but not all is waterproof. Amazon kindle oasis is latest version but quite expensive. It comes with enough storage and warm light to reduce the strain on the reader's eyes.