diff --git a/Makefile b/Makefile
index fd2d9b3..8d06a2c 100644
--- a/Makefile
+++ b/Makefile
@@ -3,5 +3,8 @@ all: build
 build:
 	@dune build
 
+doc:
+	@dune build @doc
+
 clean:
 	@dune clean
diff --git a/src/metadata.ml b/src/metadata.ml
index 4d7fab7..414ee24 100644
--- a/src/metadata.ml
+++ b/src/metadata.ml
@@ -11,6 +11,7 @@ module Make (E : CharEncoding.T) = struct
   module AVI = MetadataAVI
   module MP4 = MetadataMP4
 
+  (** Charset conversion function. *)
   let recode = E.convert
 
   module ID3 = struct
@@ -59,8 +60,15 @@ module Make (E : CharEncoding.T) = struct
 
   module Any = struct
     let parsers = Audio.parsers @ Image.parsers @ Video.parsers
+
+    (** Genering parsing of metadata. *)
     let parse = first_valid parsers
+
+    (** Parse the metadatas of a file. *)
     let parse_file = Reader.with_file parse
+
+    (** Parse the metadatas of a string. *)
+    let parse_string = Reader.with_string parse
   end
 
   include Any
diff --git a/src/metadataBase.ml b/src/metadataBase.ml
index 0b21ad2..10b0536 100644
--- a/src/metadataBase.ml
+++ b/src/metadataBase.ml
@@ -4,7 +4,10 @@ exception Invalid
 type metadata = (string * string) list
 type endianness = Big_endian | Little_endian
 
+(** Abstractions for accessing data from various sources (files, strings,
+    etc.). *)
 module Reader = struct
+
   (** A function to read taking the buffer to fill the offset and the length and
       returning the number of bytes actually read. *)
   type t = {