Fuchsia is an open-source capability-based operating system developed by Google. In contrast to Google's Linux-based operating systems such as ChromeOS and Android, Fuchsia is based on a custom kernel named Zircon. It publicly debuted as a Google-hosted git repository in August 2016 without any official corporate announcement. After years of development, its official product launch was in 2021 on the first-generation Google Nest Hub, replacing its original Linux-based Cast OS.

Fuchsia is named for the color fuchsia, which is a combination of pink and purple. The name is a reference to two operating systems projects within Apple which influenced team members of the Fuchsia project: Taligent (codenamed "Pink") and iOS (codenamed "Purple"). The color-based naming scheme derives from the colors of index cards which Apple employees used to organize their ideas.

The name of the color fuchsia is derived from the Fuchsia plant genus, which is derived from the name of botanist Leonhart Fuchs.

In August 2016, media outlets reported on a mysterious source code repository published on GitHub, revealing that Google was developing a new operating system named Fuchsia. No official announcement was made, but inspection ^{[by whom?]} of the code suggested its capability to run on various devices, including "dash infotainment" systems for cars, embedded devices like traffic lights, digital watches, smartphones, tablets, and PCs. Its architecture differs entirely from the Linux-based Android and ChromeOS due in part to its unique Zircon kernel, formerly named Magenta.

In May 2017, Ars Technica wrote about Fuchsia's new user interface, an upgrade from its command-line interface at its first reveal in August. A developer wrote that Fuchsia "isn't a toy thing, it's not a 20% Project, it's not a dumping ground of a dead thing that we don't care about anymore". Though users could test Fuchsia, nothing "works", because "it's all a bunch of placeholder interfaces that don't do anything". They found multiple similarities between Fuchsia's interface and Android, including a Recent Apps screen, a Settings menu, and a split-screen view for viewing multiple apps at once. Multiple media outlets wrote about the project's seemingly close ties to Android, with some speculating that Fuchsia might be an effort to "re-do" or replace Android in a way that fixes its problems.

In January 2018, Google published a guide on how to run Fuchsia on Pixelbooks. This was implemented successfully by Ars Technica, where experts were impressed with the progress, noting that things were then working, and were especially pleased by the hardware support and multiple mouse pointers.

A Fuchsia device was added to the Android ecosystem in January 2019 via the Android Open Source Project (AOSP). Google talked about Fuchsia at Google I/O 2019. Hiroshi Lockheimer, Senior Vice President of Chrome and Android, described it as one of Google's experiments around new operating system concepts.

On July 1, 2019, Google announced the official website of the development project with source code and documentation. Roughly a year and a half later, on December 8, 2020, Google announced that it was "expanding Fuchsia's open-source model" including making mailing lists public, introducing a governance model, publishing a roadmap, and using a public issue tracker.