diff --git a/docs/rooms/retention_policies.md b/docs/rooms/retention_policies.md
index 25425e0..9196f1c 100644
--- a/docs/rooms/retention_policies.md
+++ b/docs/rooms/retention_policies.md
@@ -5,4 +5,57 @@ date: 2021-08-03T20:30:00+02:00
 
 # Message retention policies
 
+Message retention policies exist at a room level, follow the semantics described in [MSC1763](https://github.com/matrix-org/matrix-doc/blob/matthew/msc1763/proposals/1763-configurable-retention-periods.md), and allow server and room admins to configure how long messages should be kept in a homeserver's database before being purged from it.
 
+!!! note
+	Please note that, as this feature isn't part of the Matrix specification yet, this implementation is to be considered as experimental.
+
+A message retention policy is mainly defined by its `max_lifetime` parameter, which defines how long a message can be kept around after it was sent to the room. If a room doesn't have a message retention policy, and there's no default one for a given server, then no message sent in that room is ever purged on that server.
+
+MSC1763 also specifies semantics for a `min_lifetime` parameter which defines the amount of time after which an event can get purged (after it was sent to the room), but Synapse doesn't currently support it beyond registering it.
+
+Both `max_lifetime` and `min_lifetime` are optional parameters.
+
+!!! note
+	Note that message retention policies don't apply to state events.
+
+more infomration about Message retention policies can find [here](https://github.com/matrix-org/synapse/blob/master/docs/message_retention_policies.md).
+
+## Lifetime limits on envs.net
+
+Our current instance lifetime limits are:
+
+```yaml
+  allowed_lifetime_min: 30m
+  allowed_lifetime_max: 3y
+```
+
+## Room configuration
+
+To configure a room's message retention policy, a room's admin or
+moderator needs to send a state event in that room with the type
+`m.room.retention` and the following content:
+
+* Type `/devtools`.
+* Select "Create custom event"
+* Press red "Event" button to change to "State event"
+* Set event type to `m.room.retention`
+
+```json
+{
+    "max_lifetime": ...
+}
+```
+
+Press `Send`
+
+In this event's content, the `max_lifetime` parameter has the same
+meaning as previously described, and needs to be expressed in
+milliseconds. The event's content can also include a `min_lifetime`
+parameter, which has the same meaning and limited support as previously
+described.
+
+!!! note
+	Note that over every server in the room, only the ones with support for
+	message retention policies will actually remove expired events. This
+	support is currently not enabled by default in Synapse.