Plugins extend the core functionality of JetBrains products. They provide various integrations (e.g. with a VCS or application servers), add support for various development technologies, frameworks and programming languages, and so on.
The Marketplace (AKA Plugins Repository) is a service responsible for:
Providing a product (e.g. IntelliJ IDEA) with a list of compatible plugins and their updates.
Facilitating the download of compatible plugin updates.
Storage, uploading, and management of the plugins and their updates developed and published by third-party vendors or JetBrains.
JetBrains provides an official plugins repository plugins.jetbrains.com for all IntelliJ Platform-based IDEs, as well as TeamCity, .NET, Hub (with widgets for YouTrack and Upsource.)
This documentation section includes articles, FAQs, and tutorials on JetBrains Marketplace / Plugins Repository operations.
You can always reach out to the plugin repository team via email firstname.lastname@example.org.