EMUI

EMUI, (formerly known as Emotion UI, and also known as Magic UI on Honor smartphones) is an Android-derived mobile operating system developed by Chinese technology company Huawei. It is used on the company's smartphones and tablets. 
Outside of mainland China, Huawei devices released prior to 2020 run versions of EMUI certified by Google as Android distributions, which support Google Play and other Google apps. In mainland China, and internationally since 2020 due to U.S. sanctions, EMUI devices utilise Huawei-provided services such as AppGallery instead.
History.
On 30 December 2012, Huawei introduced Emotion UI 1.0, based on Android 4.0. It features a voice assistant app (only in Chinese), customizable homescreens and theme-switching. The company rolled out installation files for the Ascend P1 through their website. The company claims that it is "probably the world's most emotional system".
On 4 September 2014, the company announced EMUI 3.0, along with Ascend Mate 7 in the pre-IFA event in Berlin. The user interface was ever since called "EMUI" instead of "Emotion UI". In Mainland China, the release introduces the Huawei AppGallery application store; international markets continued to use Google Play. 
In late 2015, Huawei introduced EMUI 4.0, based on Android Marshmallow. In 2016, EMUI 5.0 was introduced, based on Android Nougat. In 2017, Huawei introduced EMUI 8.0, based on Android Oreo; beginning with this release, the version number would now be aligned with that of the Android version from which it was derived. 
Huawei unveiled EMUI 9.0, based on Android Pie, at IFA in 2018. Huawei stated a goal for the release to make EMUI more "simple", "enjoyable", and consistent; it included various usability tweaks, reorganized settings menus, dark mode, gesture navigation, and GPU Turbo 2.0. Beginning with EMUI 9.0.1, new Huawei devices ship with the company's EROFS file system for its system partitions, which is designed for higher performance in read-only settings on devices with limited resources. In July 2019, Huawei released EMUI 9.1
EMUI 10, based on Android 10, was announced 9 August 2019 at the Huawei Developer Conference. It features an updated interface with larger "magazine"-styled headings, new animations, colour accents inspired by painter Giorgio Morandi, and Android 10's system-wide dark mode support. Beginning 2020 due to United States sanctions against Huawei (which prohibit U.S.-based companies from doing business with the company), new EMUI smartphones sold internationally (beginning with the Mate 30) are no longer certified by Google, do not include support for Google mobile services (GMS) including Google Play, and are marketed as running EMUI with no reference to the Android trademark. These devices introduce AppGallery and Huawei Mobile Services to international markets as an alternative to Google-provided software. This does not apply to Huawei models that were released prior to the sanctions (such as the P30).
In 2020 alongside the P40, Huawei announced EMUI 10.1, which adds multi-window support, and the new first-party apps Celia and MeeTime. Huawei announced updates for some of its existing devices in June 2020. In December 2020, Huawei released the HarmonyOS 2.0 beta for the P30 and P40, which iterates from EMUI 10.
Reception.
Earlier versions of EMUI have been criticized for placing all app icons on the home screen, with some reviewers saying that it tries to imitate Apple's iOS. The app drawer has been brought back as an option in EMUI 5.0. "PC Magazine" Adam Smith criticized EMUI for being bloated with duplicate apps and the settings menus being difficult to navigate.
References.
 