Fluent UI

link - developer.microsoft.com/en-us/fluentui/ 

Is a mobile first, front-end framework that you can use to apply the Office Design Language to your web experience.
This library contains everything you need including styling, components and animation.
This library is often described as a Bootstrap framework for Office, Office 365 and SharePoint.

Fluent UI React Components (v9)

The fifth iteration was released in August 2022 and was called Fluent UI React Components.
This is a combination of the Office components '@fluentui/react' and the MS Teams components '@fluentui/react-northstar'.
Nuget Package - There is no Nuget package for Fluent UI React Components
NPM Package Name - @fluentui/react-components

link - react.fluentui.dev 
link - github.com/microsoft/fluentui 
link - github.com/microsoft/fluentui/wiki/Fluent-UI-React-v9-Release 
npm install --save @fluentui/react-components 

Fluent UI React + Core (v8)

The fourth iteration was released in March 2020 and was called Fluent UI React.
link - developer.microsoft.com/en-us/office/blogs/ui-fabric-is-evolving-into-fluent-ui/
This package contains components written in React.
Nuget Package - There is no Nuget package for Fluent UI React
NPM Package Name - @fluentui/react

link - github.com/microsoft/fluentui 
npm install --save @fluentui/react 

Office UI Fabric React + Core

The third iteration was released in January 2017 and was called Office UI Fabric React.
This package contains components written in React.
Nuget Package - There is currently no Nuget package for Office UI Fabric React
Nuget Package - OfficeFabricUICore
NPM Package Name - office-ui-fabric-react
NPM Package Name - office-ui-fabric-core

link - github.com/OfficeDev/office-ui-fabric-core 

The Office UI Fabric Core package was last updated on GitHub in October 2019.
There are similar packages for AngularJS and iOS although these are not as popular and are not updated regularly.

href="https://static2.sharepointonline.com/files/fabric/office-ui-fabric-core/9.6.0/css/fabric.min.css" 

Office UI Fabric JavaScript + Core

The second iteration was released in August 2016 and was called Office UI Fabric JS.
This version took the existing Office UI Fabric package (version 1) and split it into two independent packages.
The Office UI Fabric JavaScript package contained the existing javascript components that used JQuery.
The Office UI Fabric Core package contained all the CCS classes for the appearance and styling.
Nuget Package Name - OfficeUIFabricJS
NPM Package Name - office-ui-fabric-js

link - github.com/OfficeDev/office-ui-fabric-js 
link - github.com/OfficeDev/office-ui-fabric-core 

This package is no longer being updated on Nuget or NPM and the last version was released in February 2017 (1.4.0).

href="https://static2.sharepointonline.com/files/fabric/office-ui-fabric-js/1.4.0/css/fabric.min.css" 
href="https://static2.sharepointonline.com/files/fabric/office-ui-fabric-js/1.4.0/css/fabric.components.min.css" 

Office UI Fabric

The first iteration was released in August 2015 and was called Office UI Fabric.
This contained javascript components that used JQuery with CSS classes for the appearance and styling.
Nuget Package Name - OfficeUIFabric
NPM Package Name - office-ui-fabric
This package is no longer being updated on Nuget or NPM and the last version was released in [[February 2017 (2.6.3)]]

href="https://appsforoffice.microsoft.com/fabric/2.6.3/fabric.min.css" 
href="https://appsforoffice.microsoft.com/fabric/2.6.3/fabric.components.min.css"