Here are some examples of the central services provided by the OpenACS toolkit.

• The Permissions System gives the programmer fine-grained control over which users can take which actions on specific objects.

• The General Comments package provides a datamodel and user interface that allows visitors to add comments to any object in the system.

• The Attachments package provides a datamodel and user interface that allows users to add attachments (photos, videos, etc) to objects they create.

• The Notification package provides a datamodel and user interface that allows users to request notification (by e-mail, for instance) when an action specified by the package programmer takes place on objects the package controls (for instance a new post to a forum).

• The Categorization package allows one to categorize content throughout an OpenACS installation.