You can save and load `IContent` instances through `IContentRepository`. The most typical content instance is a type inheriting `PageData`. You can load and save content types other than pages but those content instances do not appear in the editorial interface's page tree.

Each `IContent` stored in the Optimizely Content Management System (CMS) content database must have a corresponding `ContentType` registered. Classes annotated with the `ContentType` attribute are automatically scanned for and registered during initialization.

The following example uses the `Comment` class to define and persist a `Comment` type. To implement comment functionality, each comment can be saved as an `IContent` under the page that is commented. However, the comments do not appear in the page tree.

## Define a comment content type

## Save and load comment

The following example creates a `Comment` instance, saves it, and re-loads it. Use `IContentRepository` to create, load, and save content instances.