As of May 2017, Apple has sold more than 360 million iPads though sales peaked in 2013, it is the most popular tablet computer by sales as of the second quarter of 2018.
The user interface is built around the device's multi-touch screen, including a virtual keyboard. All iPads can connect using Wi-Fi; some models also have cellular connectivity. iPads can shoot video, take photos, play music, and perform Internet functions such as web-browsing and emailing. Other functions – games, reference, GPS navigation, social networking, etc. – can be enabled by downloading and installing apps. As of March 2016, the App Store has more than 1 million apps for the iPad by Apple and third parties.
The deals for Samsung tablets continue to improve following the recent announcement of the Samsung Tab S7 (not yet available for purchase). The Android tablet platform-leading Samsung Galaxy Tab lineup has really come into their own, offering an excellent mobile experience outside the apple iPad tablet’s iPad OS software ecosystem. If you’re hunting for tablet deals and want something that shares apps with an Android phone, then you want a Galaxy Tab. The Tab line covers a nice range of prices to fit any budget, too, but to save you even more, we’ve rounded up the best cheap Samsung Galaxy Tab deals you can find online right now along with a run-down of the current models on the market today.
Amazon's new Fire HD 10 tablet costs half as much as an iPad but is still a really great tablet. It has a decent screen, great battery life and finally has new charging technology. It's perfect for watching movies, reading books, listening to Audible or using Amazon's other services. This new item in the market can give iPad a tough competition.
Reasons for dominance of Apple 
Apple shipped 12.4 million units in 2Q20 to capture the top position once again.
Samsung retained the number two position and recorded year-over-year shipment growth of 42.5%.
Amazon regained the fourth position with growth of 52.0% year over year. .Amazon launched new 8-inch Fire HD tablets with upgraded processor and storage to cater to users looking for inexpensive devices for content consumption.
Major Factors: 
Shipments dropped 4% YoY to 38.2 million units in Q3. Huawei and Samsung led the decline in tablet shipments, offset by Apple, Amazon (AMZN), and Lenovo.
Apple’s decision to rejig its portfolio toward a cheaper iPad spurred demand. In September, Apple released new iPads with a 10.2-inch screen and smart keyboard support for just $329. These low-cost iPads have also been instrumental in driving sales.
Challenges for Apple 
Like the iPhone, iPads talk to Siri and have a standardized display, uniform unlocking animations, the gray and white keyboard, etc. Limited customization options lead to that clean, user-friendly display, making iPads easy to get the hang of.
Apple catches heat for its tablets being so expensive, but with blisteringly fast processing speeds, gorgeous liquid retina displays, and processing chips made to handle work and creative projects, the price is justified. Luckily, multiple display size and storage options mitigate the price tag. On a good day, you can score the 2018 iPad for less than $300.
Advantages of Amazon and Samsung
Formerly called the Kindle Fire, the Amazon Fire HD Tablets are Amazon's Kindle version of the tablet. Unlike Kindles, these tablets operate similarly to an iPad in that they are a color touchscreen, have Alexa built-in, and can be used to watch content, play games, draw, and take live notes. All this; they get the job done with simplicity and at a low cost.
Where Samsung actually beats iPad is with its 13 MP rear camera, battery life, and the new and improved S Pen. Samsung's S Pen is the stylus equivalent to the Apple Pencil and has numerous hovering air commands like note taking and creating GIFs from videos. The S Pen is actually included in the purchase of all Galaxy Tabs, while Apple's is an extra $99 — rude). It also never needs charging.
Domination of iPad will continue.
In integration to its price advantage, Apple has the luxury of being able to push its tablet out through its own Apple Store retail channel. This integrates an extra few points of margin to every iPad sold that doesn’t have to have another slice taken off by an outside retailer. It gives people a psychologically positive environment in which to pick up and play with an iPad.
The mostly ebullient and erudite staff at Apple Retail Stores and the unsullied, well designed atmosphere are a far cry from the experience that most people will have when endeavoring out an Android, QNX or WebOS tablet for the first time.
A tablet may not be as hard of a sell now as it was two years ago, but it’s definitely still a product that many people need avail justifying the purchase of. Having evangelized the tablet platform since day one, I can tell you that there is no supersession for a few quality minutes of hands-on time to convince Moms, grandparents and other skeptics that a responsive, well-designed tablet does have its benefits over a laptop.
First impressions are incredibly consequential, especially for a contrivance that is defining an incipient class of product entirely. Apple’s 336 Retail Stores gave customers a fantastic first impression of the iPad and perpetuate to sanction Apple to sell the iPad at better margins, without having to make deals that cut into its profit.
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- https://marketrealist.com/2019/11/apple-will-the-ipad-continue-to-dominate/ Date[Oct-2019]
- https://mashable.com/roundup/what-tablet-is-the-best-amazon-samsung-apple/ Date[July-2019]
- https://thenextweb.com/apple/2011/08/14/why-the-ipad-has-and-will-continue-to-dominate-the-tablet-market/ Date[Aug-2011]