diff --git a/src/lib/slacko.ml b/src/lib/slacko.ml
index 6261b26..4d30b25 100644
--- a/src/lib/slacko.ml
+++ b/src/lib/slacko.ml
@@ -195,6 +195,8 @@ type channel = ChannelId of string | ChannelName of string
 
 type conversation = string
 
+type im = string
+
 type user = UserId of string | UserName of string
 
 type bot = BotId of string
@@ -202,7 +204,7 @@ type bot = BotId of string
 type group = GroupId of string | GroupName of string
 
 (* TODO: Sure about user? *)
-type chat = Channel of channel | Im of conversation | User of user | Group of group
+type chat = Channel of channel | Im of im | User of user | Group of group
 
 type sort_criterion = Score | Timestamp
 
@@ -226,13 +228,17 @@ let channel_of_yojson = function
   | `String x -> Ok (ChannelId x)
   | _ -> Error "Couldn't parse channel type"
 
+let conversation_of_yojson = function
+  | `String x -> Ok x
+  | _ -> Error "Couldn't parse conversation type"
+
 let group_of_yojson = function
   | `String x -> Ok (GroupId x)
   | _ -> Error "Couldn't parse group type"
 
-let conversation_of_yojson = function
+let im_of_yojson = function
   | `String x -> Ok x
-  | _ -> Error "Couldn't parse conversation type"
+  | _ -> Error "Couldn't parse im type"
 
 type topic_obj = {
   value: string;
@@ -259,6 +265,25 @@ type channel_obj = {
   num_members: int option [@default None];
 } [@@deriving of_yojson { strict = false }]
 
+type conversation_obj = {
+  id: conversation;
+  name: string;
+  is_channel: bool;
+  created: Timestamp.t;
+  creator: user;
+  is_archived: bool;
+  is_general: bool;
+  is_member: bool;
+  topic: topic_obj;
+  purpose: topic_obj;
+  last_read: Timestamp.t option [@default None];
+  latest: string option [@default None];
+  unread_count: int option [@default None];
+  unread_count_display: int option [@default None];
+  num_members: int option [@default None];
+} [@@deriving of_yojson { strict = false }]
+
+
 type user_obj = {
   id: user;
   name: string;
@@ -336,7 +361,7 @@ type file_obj = {
   (*public_url_shared: ???;*)
   channels: channel list;
   groups: group list;
-  ims: conversation list;
+  ims: im list;
   initial_comment: Yojson.Safe.t option [@default None];
   num_stars: int option [@default None];
 } [@@deriving of_yojson { strict = false }]
@@ -485,6 +510,8 @@ type im_obj = {
   user: user;
   created: Timestamp.t;
   is_user_deleted: bool;
+  is_open: bool option [@default None];
+  last_read: Timestamp.t option [@default None];
   unread_count: int option [@default None];
   unread_count_display: int option [@default None];
 } [@@deriving of_yojson { strict = false }]
@@ -883,8 +910,8 @@ let user_of_string s =
 let group_of_string s =
   if s.[0] = 'G' then GroupId s else GroupName s
 
-(* TODO Create a conversation if conversation does not exist? *)
-let conversation_of_string s =
+(* TODO Create a im if im does not exist? *)
+let im_of_string s =
   if s.[0] = 'D' then s else failwith "Not an IM channel"
 
 let translate_parsing_error = function
diff --git a/src/lib/slacko.mli b/src/lib/slacko.mli
index 901b321..54c4064 100644
--- a/src/lib/slacko.mli
+++ b/src/lib/slacko.mli
@@ -279,9 +279,12 @@ type message
     channel id. *)
 type channel
 
-(** A type of an IM conversation *)
+(** A channel-like container for a conversation used by the Conversations API. *)
 type conversation
 
+(** A type of an IM conversation *)
+type im
+
 (** An user, represented by either a user name or a user id. *)
 type user
 
@@ -292,7 +295,7 @@ type bot
 type group
 
 (** A place one can post messages to. *)
-type chat = Channel of channel | Im of conversation | User of user | Group of group
+type chat = Channel of channel | Im of im | User of user | Group of group
 
 (** What criterion to use in search. *)
 type sort_criterion = Score | Timestamp
@@ -368,6 +371,25 @@ type channel_obj = {
   num_members: int option;
 }
 
+(** Object representing information about a Slack channel. *)
+type conversation_obj = {
+  id: conversation;
+  name: string;
+  is_channel: bool;
+  created: timestamp;
+  creator: user;
+  is_archived: bool;
+  is_general: bool;
+  is_member: bool;
+  topic: topic_obj;
+  purpose: topic_obj;
+  last_read: timestamp option;
+  latest: string option;
+  unread_count: int option;
+  unread_count_display: int option;
+  num_members: int option;
+}
+
 (** Object representing a message attachment field. *)
 type field_obj = {
   title: string option;
@@ -468,13 +490,15 @@ type groups_rename_obj = {
   created: timestamp
 }
 
-(** Information about a direct conversation with a person. *)
+(** Information about a direct im with a person. *)
 type im_obj = {
   id: string;
   is_im: bool;
   user: user;
   created: timestamp;
   is_user_deleted: bool;
+  is_open: bool option;
+  last_read: timestamp option;
   unread_count: int option;
   unread_count_display: int option;
 }
@@ -483,7 +507,7 @@ type im_channel_obj = {
   id: string;
 }
 
-(** Information about an direct conversation channel. *)
+(** Information about an direct im channel. *)
 type im_open_obj = {
   no_op: bool option;
   already_open: bool option;
@@ -555,7 +579,7 @@ type file_obj = {
   (*public_url_shared: ???;*)
   channels: channel list;
   groups: group list;
-  ims: conversation list;
+  ims: im list;
   initial_comment: Yojson.Safe.t option;
   num_stars: int option;
 }
@@ -690,9 +714,9 @@ val bot_of_string : string -> bot
     id by means of an additional request. *)
 val channel_of_string: string -> channel
 
-(** Create a conversation type out of a given string. The string is usually
-    starting with a capital 'D' and represents an IM conversation channel. *)
-val conversation_of_string: string -> conversation
+(** Create a im type out of a given string. The string is usually
+    starting with a capital 'D' and represents an IM im channel. *)
+val im_of_string: string -> im
 
 (** {2 Slack API calls} *)
 
@@ -823,16 +847,16 @@ val groups_set_topic: session -> group -> topic -> topic_result Lwt.t
 val groups_unarchive: session -> group -> [ `Success | parsed_auth_error | channel_error | `Not_archived | `User_is_restricted | bot_error ] Lwt.t
 
 (** Close a direct message channel. *)
-val im_close: session -> conversation -> [ `Success of chat_close_obj | parsed_auth_error | channel_error | `User_does_not_own_channel ] Lwt.t
+val im_close: session -> im -> [ `Success of chat_close_obj | parsed_auth_error | channel_error | `User_does_not_own_channel ] Lwt.t
 
 (** Fetches history of messages and events from direct message channel. *)
-val im_history: session -> ?latest:timestamp -> ?oldest:timestamp -> ?count:int -> ?inclusive:bool -> conversation -> history_result Lwt.t
+val im_history: session -> ?latest:timestamp -> ?oldest:timestamp -> ?count:int -> ?inclusive:bool -> im -> history_result Lwt.t
 
 (** Lists direct message channels for the calling user. *)
 val im_list: session -> [ `Success of im_obj list | parsed_auth_error ] Lwt.t
 
 (** Sets the read cursor in a direct message channel. *)
-val im_mark: session -> conversation -> timestamp -> [ `Success | parsed_auth_error | channel_error | not_in_channel_error ] Lwt.t
+val im_mark: session -> im -> timestamp -> [ `Success | parsed_auth_error | channel_error | not_in_channel_error ] Lwt.t
 
 (** Opens a direct message channel. *)
 val im_open: session -> user -> [ `Success of im_open_obj | parsed_auth_error | user_error | user_visibility_error ] Lwt.t
diff --git a/test/test_slacko.ml b/test/test_slacko.ml
index c93a20b..49fad12 100644
--- a/test/test_slacko.ml
+++ b/test/test_slacko.ml
@@ -292,13 +292,13 @@ let groups_list_tests = fake_slack_tests "groups_list" [
 
 let test_im_history_bad_auth _tctx =
   let session = Slacko.start_session ?base_url badtoken in
-  let slackbot = Slacko.conversation_of_string Fake_slack.im_slackbot in
+  let slackbot = Slacko.im_of_string Fake_slack.im_slackbot in
   Slacko.im_history session slackbot >|= fun resp ->
   assert_equal `Invalid_auth resp
 
 let test_im_history_no_params _tctx =
   let session = Slacko.start_session ?base_url token in
-  let slackbot = Slacko.conversation_of_string Fake_slack.im_slackbot in
+  let slackbot = Slacko.im_of_string Fake_slack.im_slackbot in
   Slacko.im_history session slackbot >|= get_success >|= fun history ->
   assert_equal ~printer:show_abbr_history_obj
     (abbr_json abbr_history_obj_of_yojson Fake_slack.slackbot_history_json)