# ActivityItem

Represents a change in an issue or in its related entities. In the YouTrack UI, you see these changes in the activity stream. It shows a list of all changes related to this issue: the issue history, comments, attachments, VCS changes, work items, and so on.

## Related Resources

Below you can find the list of resources that let you work with this entity.

* [Activities](resource-api-activities.html)

* [Issue Activity Items](resource-api-issues-issueID-activities.html)

Extended by:

* [CreatedDeletedActivityItem](api-entity-CreatedDeletedActivityItem.html)

* [SingleValueActivityItem](api-entity-SingleValueActivityItem.html)

* [MultiValueActivityItem](api-entity-MultiValueActivityItem.html)

* [CustomFieldActivityItem](api-entity-CustomFieldActivityItem.html)

## Attributes

This table describes attributes of the `ActivityItem` entity.

* To receive an attribute in the response from the server, specify it explicitly in the `fields` request parameter.

* To update an attribute, provide it in the body of a POST request.

|  Field  |  Type  |  Description  |
| --- | --- | --- |
|  id  |  String  |  The ID of the activity item. `Read-only`.  |
|  added  |   |  Single value or the list of values which were added to a property of the target entity. `Read-only`.  |
|  author  |  [User](api-entity-User.html)  |  The user who performed the action. `Read-only`.  |
|  category  |  [ActivityCategory](api-entity-ActivityCategory.html)  |  The category of the activity. `Read-only`.  |
|  field  |  [FilterField](api-entity-FilterField.html)  |  The filter field. It contains the additional information about the modified property in the target entity. For example, the information about a link type, or the type of the modified custom field or bundle, and so on. `Read-only`. `Can be null`.  |
|  removed  |   |  Single value or the list of values which were removed from a property of the target entity. `Read-only`.  |
|  target  |   |  The entity that is the target of the performed action. `Read-only`.  |
|  targetMember  |  String  |  The name of the property of the target entity, which was modified. `Read-only`. `Can be null`.  |
|  timestamp  |  Long  |  The timestamp of the activity event. Stored as a unix timestamp at UTC. `Read-only`.  |