diff --git a/source/Network/Xmpp/IM/PresenceTracker/Types.hs b/source/Network/Xmpp/IM/PresenceTracker/Types.hs
new file mode 100644
index 0000000..4dc412c
--- /dev/null
+++ b/source/Network/Xmpp/IM/PresenceTracker/Types.hs
@@ -0,0 +1,16 @@
+module Network.Xmpp.IM.PresenceTracker.Types where
+
+import           Data.Map (Map)
+
+import           Network.Xmpp.Types
+import           Network.Xmpp.IM.Presence
+
+-- Map from bare JIDs to a map of full JIDs to show maybe status.
+--
+-- Invariants:
+-- * The outer map should not have entries for bare JIDs that have no
+--   available resource, i.e. the inner map should never be empty
+--
+-- * The inner map keys' local and domain part coincide with the outer keys'
+newtype Peers = Peers { unPeers :: Map Jid (Map Jid (Maybe IMPresence))}
+                deriving (Show)