ESIM

An embedded-SIM (eSIM), or embedded universal integrated circuit card (eUICC), is a form of programmable SIM card that is embedded directly into a device. 
Overview.
In machine-to-machine (M2M) applications, where there is no requirement to change the SIM card, this avoids the requirement for a connector. This improves reliability and network security, while also reducing space requirements, since a relatively bulky connector is no longer needed, increasing design flexibility. An eSIM can be provisioned remotely; end-users can add or remove operators without the need to physically swap a SIM from the device.
eSIM is a global specification by the GSMA that enables remote SIM provisioning of any mobile device. GSMA defines eSIM as the SIM for the next generation of connected consumer device. Networking solutions using eSIM technology can be widely applicable to various Internet of Things (IoT) scenarios, including connected cars (smart rearview mirrors, on-board diagnostics (OBD), vehicle Wi-Fi hotspots), artificial intelligence translators, MiFi devices, smart earphones, smart metering, GPS tracking units, DTU, bike-sharing, advertising players, video surveillance devices, etc.
The surface mount format provides the same electrical interface as the full size, 2FF, 3FF and 4FF SIM cards but is soldered to a circuit board as part of the manufacturing process. The eSIM format is commonly designated "MFF2".
History.
Since 2010, the GSMA had been discussing the possibility of a software-based SIM. 
While Motorola noted that eUICC is geared at industrial devices, Apple "disagreed that there is any statement forbidding the use of an embedded UICC in a consumer product." 
A first version of the standard was published in March 2016, followed by a second version in November 2016.
In 2016, the Samsung Gear S2 Classic 3G smartwatch was the first device to implement an eSIM.
In 2017, during Mobile World Congress, Qualcomm introduced a technical solution, with a live demonstration, within its Snapdragon hardware chip associated with related software (secured Java applications).
Implementations.
The European Commission selected in 2012 the embedded UICC format for its in-vehicle emergency call service, known as eCall. All new car models in the EU must have one by 2018 to instantly connect the car to emergency services in case of an accident.
Russia has a similar plan with the GLONASS (national satellite positioning system) called ERA-GLONASS. 
Singapore is seeking public opinions on introducing eSIM as a new standard, as more compatible devices enter the market.
Apple implemented eSIM support in its Apple Watch Series 3 and later, in addition to every iPad they've released since the iPad Pro (2018). Apple also included eSIM support with the iPhone XS and later. eSIM support on iPhone requires iOS 12.1 or later. Not all iPhones sold worldwide have eSIM support; Apple removed this feature from models intended for mainland China. Apple has seven worldwide service providers that offer eSIM service: GigSky, MTX Connect, Redtea Mobile, Soracom Mobile, Truphone, Ubigi, and Webbing.
Google unveiled the Pixel 2 in October 2017, which added eSIM support for use with its Google Fi service. In 2018, Google released the Pixel 3 and Pixel 3 XL and subsequently in May 2019, the Pixel 3a and Pixel 3a XL, with eSIM support for carriers other than Google Fi. In October that same year, Google released the Pixel 4 and Pixel 4 XL with eSIM support. 
Motorola released the 2020 version of the Motorola Razr, a foldable smartphone that has no physical SIM slot since it only supports eSIM.
Plintron implemented the eSIM4Things Internet of things product, based on eSIM support for the devices and available in 28 countries.
Microsoft introduced eSIM to the Windows 10 operating system in 2018 and launched its first eSIM-enabled device, Surface Pro LTE, in 2017.