https://www.w3.org/TR/activitystreams-core/

Types:

From https://www.w3.org/TR/activitystreams-vocabulary/#types

• Object
• Link
• Activity
• IntransitiveActivity
• Collection
• OrderedCollection
• CollectionPage
• OrderedCollectionPage

• Accept
• Add
• Announce
• Arrive
• Block
• Create
• Delete
• Dislike
• Flag
• Follow
• Ignore
• Invite
• Join
• Leave
• Like
• Listen
• Move
• Offer
• Question
• Reject
• Read
• Remove
• TentativeReject
• TentativeAccept
• Travel
• Undo
• Update
• View

• Application
• Group
• Organization
• Person
• Service

• Article
• Audio
• Document
• Event
• Image
• Note
• Page
• Place
• Profile
• Relationship
• Tombstone
• Video

Link type includes Mention

• Mention