Apple Watch is a line of smartwatches developed, designed, and marketed by Apple Inc. It incorporates fitness tracking and health-oriented capabilities with integration with iOS and other Apple products and services.

The original generation of the device was available in four variants: Apple Watch Sport, Apple Watch, Apple Watch Hermès, and Apple Watch Edition; each distinguished by different combinations of cases and first- or third-party interchangeable bands.

Apple Watch relies on a wirelessly connected iPhone to perform many of its default functions such as calling and texting.

It is compatible with the iPhone 5 or later models running iOS 8.2 or later, through the use of Wi-Fi or Bluetooth.

Announced by Apple CEO Tim Cook in September 2014, the device was released in April 2015.

The Apple Watch quickly became the best-selling wearable device with the supply of 4.2 million smartwatches in the second quarter of the 2015 fiscal year.

The second generation of Apple Watch, released in September 2016, includes two tiers: Apple Watch Series 2 and Apple Watch Series 1, which includes the S1P chip, but is otherwise identical to the original.

A cryptocurrency (or crypto currency) is a digital asset designed to work as a medium of exchange using cryptography to secure the transactions and to control the creation of additional units of the currency.

Cryptocurrencies are a subset of alternative currencies, or specifically of digital currencies.

iPhone is a line of smartphones designed and marketed by Apple Inc. They run Apple's iOS mobile operating system.

The first generation iPhone was released on June 29, 2007; the most recent iPhone model is the iPhone 7, which was unveiled at a special event on September 7, 2016.

iPad is a line of tablet computers designed, developed and marketed by Apple Inc., which run the iOS mobile operating system.

The first iPad was released on April 3, 2010; the most recent iPad models are the 9.7-inch iPad Pro released on March 31, 2016 and the iPad Mini 4, released on September 9, 2015.

The user interface is built around the device's multi-touch screen, including a virtual keyboard.

The iPad includes built-in Wi-Fi and cellular connectivity on select models.

As of January 2015, there have been over 250 million iPads sold.

iPad tablets are second most popular, by sales, against Android-based ones, since 2013, when Android tablet sales increased by 127%.

Cryptography or cryptology (from Greek kryptós, "hidden, secret"; and graphein, "writing", or -logia, "study", respectively) is the practice and study of techniques for secure communication in the presence of third parties called adversaries.

More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the public from reading private messages; various aspects in information security such as data confidentiality, data integrity, authentication, and non-repudiation are central to modern cryptography.

Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, and electrical engineering.

Applications of cryptography include ATM cards, computer passwords, and electronic commerce.