diff --git a/src/main/java/envoy/data/LoginCredentials.java b/src/main/java/envoy/data/LoginCredentials.java
index 86b166c..a8d9c6b 100644
--- a/src/main/java/envoy/data/LoginCredentials.java
+++ b/src/main/java/envoy/data/LoginCredentials.java
@@ -9,55 +9,29 @@ import java.util.Formatter;
  * Project: <strong>envoy-common</strong><br>
  * File: <strong>LoginCredentials.java</strong><br>
  * Created: <strong>29.12.2019</strong><br>
- * 
+ *
  * @author Kai S. K. Engelbart
  * @since Envoy Common v0.2-alpha
  */
 public class LoginCredentials implements Serializable {
 
-	private final String	name;
-	private final byte[]	passwordHash;
-
-	private static final long serialVersionUID = -7395245059059523314L;
+	private static final long	serialVersionUID	= -7395245059059523314L;
+	private final String		name;
+	private final byte[]		passwordHash;
 
 	/**
 	 * Creates an in stance of {@link LoginCredentials}.
-	 * 
+	 *
 	 * @param name     the name of the user
 	 * @param password the password of the user (will be converted to a hash)
-	 * @throws NoSuchAlgorithmException
+	 * @throws NoSuchAlgorithmException if the algorithm used is unknown
+	 * @since Envoy Common v0.2-alpha
 	 */
 	public LoginCredentials(String name, char[] password) throws NoSuchAlgorithmException {
 		this.name		= name;
 		passwordHash	= getSha256(toByteArray(password));
 	}
 
-	@Override
-	public String toString() {
-		Formatter form = new Formatter();
-		form.format("LoginCredentials[name=%s,passwordHash=", name);
-		for (int i = 0; i < passwordHash.length; i++)
-			form.format("%02x", passwordHash[i]);
-		form.format("]");
-		String str = form.toString();
-		form.close();
-		return str;
-	}
-
-	private byte[] toByteArray(char[] chars) {
-		byte[] bytes = new byte[chars.length * 2];
-		for (int i = 0; i < chars.length; ++i) {
-			bytes[i * 2]		= (byte) (chars[i] >> 8);
-			bytes[i * 2 + 1]	= (byte) (chars[i]);
-		}
-		return bytes;
-	}
-
-	private byte[] getSha256(byte[] input) throws NoSuchAlgorithmException {
-		MessageDigest md = MessageDigest.getInstance("SHA-256");
-		return md.digest(input);
-	}
-
 	/**
 	 * @return the name of the user performing the login
 	 * @since Envoy Common v0.2-alpha
@@ -69,4 +43,31 @@ public class LoginCredentials implements Serializable {
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public byte[] getPasswordHash() { return passwordHash; }
+
+	private byte[] getSha256(byte[] input) throws NoSuchAlgorithmException {
+		MessageDigest md = MessageDigest.getInstance("SHA-256");
+		return md.digest(input);
+	}
+
+	private byte[] toByteArray(char[] chars) {
+		byte[] bytes = new byte[chars.length * 2];
+		for (int i = 0; i < chars.length; ++i) {
+			bytes[i * 2]		= (byte) (chars[i] >> 8);
+			bytes[i * 2 + 1]	= (byte) (chars[i]);
+		}
+		return bytes;
+	}
+
+	@Override
+	public String toString() {
+		try (Formatter form = new Formatter()) {
+			form.format("LoginCredentials[name=%s,passwordHash=", name);
+			for (byte element : passwordHash) {
+				form.format("%02x", element);
+			}
+			form.format("]");
+			String str = form.toString();
+			return str;
+		}
+	}
 }
\ No newline at end of file
diff --git a/src/main/java/envoy/data/Message.java b/src/main/java/envoy/data/Message.java
index 555c751..acb3d6f 100644
--- a/src/main/java/envoy/data/Message.java
+++ b/src/main/java/envoy/data/Message.java
@@ -1,7 +1,9 @@
 package envoy.data;
 
 import java.io.Serializable;
+import java.text.SimpleDateFormat;
 import java.util.Date;
+import java.util.Optional;
 
 /**
  * Represents a unique message with a unique, numeric ID. Further metadata
@@ -11,68 +13,121 @@ import java.util.Date;
  * Project: <strong>envoy-common</strong><br>
  * File: <strong>Message.java</strong><br>
  * Created: <strong>28.12.2019</strong><br>
- * 
+ *
  * @author Kai S. K. Engelbart
+ * @author Leon Hofmeister
  * @since Envoy Common v0.2-alpha
  */
 public abstract class Message implements Serializable {
 
-	private final long	id;
-	private final User	sender, recipient;
-	private final Date	date;
+	/**
+	 * This enum defines all possible statuses a {link Message} can have.
+	 *
+	 * @since Envoy Common v0.2-alpha
+	 */
+	public static enum MessageStatus {
+
+		/**
+		 * is selected, if a message was sent but not received by the server yet.
+		 */
+		WAITING,
+
+		/**
+		 * is selected, if a sent message was received by the server.
+		 */
+		SENT,
+
+		/**
+		 * is selected, if a message was delivered from the server to the recipient, but
+		 * has not been read yet.
+		 */
+		RECEIVED,
+
+		/**
+		 * is selected, if a recipient opened the corresponding chat of said message.
+		 */
+		READ
+	}
+
+	private static final long	serialVersionUID	= -4393477412979594435L;
+	private final long			id;
+
+	private final User sender, recipient;
+
+	private final Date date;
+
+	private final String text;
+
+	private final MessageAttachment<?> messageAttachment;
 
 	private MessageStatus status;
 
-	private static final long serialVersionUID = -4393477412979594435L;
-
 	/**
 	 * Initializes a {@link Message} from the client's perspective. The current date
 	 * is used as the message date and the status is set to
 	 * {@link MessageStatus#WAITING}.
-	 * 
-	 * @param id        unique ID
-	 * @param sender    the user who sends the message
-	 * @param recipient the user who receives the message
+	 *
+	 * @param <T>        the type of the attachment
+	 * @param id         unique ID
+	 * @param sender     the user who sends the message
+	 * @param recipient  the user who receives the message
+	 * @param text       the text content of the message
+	 * @param attachment the attachment of the message, if present
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public Message(long id, User sender, User recipient) {
-		this.id			= id;
-		this.sender		= sender;
-		this.recipient	= recipient;
-		date			= new Date();
-		status			= MessageStatus.WAITING;
+	public <T> Message(long id, User sender, User recipient, String text, @SuppressWarnings("rawtypes") Optional<MessageAttachment> attachment) {
+		this.id					= id;
+		this.sender				= sender;
+		this.recipient			= recipient;
+		this.text				= text;
+		this.messageAttachment	= attachment.isEmpty() ? null : attachment.get();
+		this.date				= new Date();
+		this.status				= MessageStatus.WAITING;
 	}
 
-	/**
-	 * @return the ID of this message
-	 * @since Envoy Common v0.2-alpha
-	 */
-	public long getId() { return id; }
-
-	/**
-	 * @return the sender of this message
-	 * @since Envoy Common v0.2-alpha
-	 */
-	public User getSender() { return sender; }
-
-	/**
-	 * @return the recipient of this message
-	 * @since Envoy Common v0.2-alpha
-	 */
-	public User getRecipient() { return recipient; }
-
 	/**
 	 * @return the date at which this message was created
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public Date getDate() { return date; }
 
+	/**
+	 * @return the ID of this message
+	 * @since Envoy Common v0.2-alpha
+	 */
+	public long getId() { return id; }
+
+	/**
+	 * @param <T> the type of the message attachment
+	 * @return the messageAttachment
+	 * @since Envoy Common v0.2-alpha
+	 */
+	public <T> MessageAttachment<?> getMessageAttachment() { return messageAttachment; }
+
+	/**
+	 * @return the recipient of this message
+	 * @since Envoy Common v0.2-alpha
+	 */
+	public User getRecipient() { return recipient; }
+
+	/**
+	 * @return the sender of this message
+	 * @since Envoy Common v0.2-alpha
+	 */
+	public User getSender() { return sender; }
+
 	/**
 	 * @return the current status of this message
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public MessageStatus getStatus() { return status; }
 
+	/**
+	 * @return the text content of this message
+	 * @since Envoy Common v0.2-alpha
+	 */
+	public String getText() { return text; }
+
 	/**
 	 * Changes the current {@link MessageStatus} to the next logical status.<br>
 	 * <br>
@@ -83,7 +138,7 @@ public abstract class Message implements Serializable {
 	 * <li>{@link MessageStatus#RECEIVED}
 	 * <li>{@link MessageStatus#READ}
 	 * </ol>
-	 * 
+	 *
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public void nextStatus() {
@@ -91,7 +146,14 @@ public abstract class Message implements Serializable {
 		status = MessageStatus.values()[status.ordinal() + 1];
 	}
 
-	public static enum MessageStatus {
-		WAITING, SENT, RECEIVED, READ
+	@Override
+	public String toString() {
+		return String.format("TextMessage[id=%d,sender=%s,recipient=%s,date=%s,status=%s,content=%s]",
+				id,
+				sender,
+				recipient,
+				new SimpleDateFormat("dd.MM.yyyy HH:mm:ss").format(date),
+				status,
+				text);
 	}
 }
\ No newline at end of file
diff --git a/src/main/java/envoy/data/MessageAttachment.java b/src/main/java/envoy/data/MessageAttachment.java
new file mode 100644
index 0000000..fa86998
--- /dev/null
+++ b/src/main/java/envoy/data/MessageAttachment.java
@@ -0,0 +1,26 @@
+package envoy.data;
+
+import java.io.Serializable;
+
+import javax.swing.Scrollable;
+
+/**
+ * This Interface should be used for any type supposed to be a {@link Message}
+ * attachment (i.e. images or sound).<br>
+ * <br>
+ * Project: <strong>envoy-common</strong><br>
+ * File: <strong>MessageAttachment.java</strong><br>
+ * Created: <strong>30 Dec 2019</strong><br>
+ *
+ * @author Leon Hofmeister
+ * @param <T> the type of this message attachment
+ * @since Envoy Common v0.2-alpha
+ */
+public interface MessageAttachment<T> extends Serializable, Scrollable {
+
+	/**
+	 * @return the type implementing this interface
+	 * @since Envoy Common v0.2-alpha
+	 */
+	T get();
+}
diff --git a/src/main/java/envoy/data/TextMessage.java b/src/main/java/envoy/data/TextMessage.java
deleted file mode 100644
index cbee210..0000000
--- a/src/main/java/envoy/data/TextMessage.java
+++ /dev/null
@@ -1,54 +0,0 @@
-package envoy.data;
-
-import java.text.SimpleDateFormat;
-
-/**
- * Represents a {@link Message} with content that is comprised of text.<br>
- * <br>
- * Project: <strong>envoy-common</strong><br>
- * File: <strong>TextMessage.java</strong><br>
- * Created: <strong>28.12.2019</strong><br>
- * 
- * @author Kai S. K. Engelbart
- * @since Envoy Common v0.2-alpha
- */
-public class TextMessage extends Message {
-
-	private final String content;
-
-	private static final long serialVersionUID = 1538164720632899917L;
-
-	/**
-	 * Initializes a {@link TextMessage} from the client's perspective. The current
-	 * date
-	 * is used as the message date and the status is set to
-	 * {@link envoy.data.Message.MessageStatus#WAITING}.
-	 * 
-	 * @param id        unique ID
-	 * @param sender    the user who sends the message
-	 * @param recipient the user who receives the message
-	 * @param content   the content of the message
-	 * @since Envoy Common v0.2-alpha
-	 */
-	public TextMessage(long id, User sender, User recipient, String content) {
-		super(id, sender, recipient);
-		this.content = content;
-	}
-
-	@Override
-	public String toString() {
-		return String.format("TextMessage[id=%d,sender=%s,recipient=%s,date=%s,status=%s,content=%s]",
-				getId(),
-				getSender(),
-				getRecipient(),
-				new SimpleDateFormat("dd.MM.yyyy HH:mm:ss").format(getDate()),
-				getStatus(),
-				content);
-	}
-
-	/**
-	 * @return the content of this {@link TextMessage}
-	 * @since Envoy Common v0.2-alpha
-	 */
-	public String getContent() { return content; }
-}
\ No newline at end of file
diff --git a/src/main/java/envoy/data/User.java b/src/main/java/envoy/data/User.java
index afca690..6109218 100644
--- a/src/main/java/envoy/data/User.java
+++ b/src/main/java/envoy/data/User.java
@@ -9,23 +9,53 @@ import java.io.Serializable;
  * Project: <strong>envoy-common</strong><br>
  * File: <strong>User.java</strong><br>
  * Created: <strong>28.12.2019</strong><br>
- * 
+ *
  * @author Kai S. K. Engelbart
  * @since Envoy Common v0.2-alpha
  */
 public class User implements Serializable {
 
-	private final long		id;
-	private final String	name;
+	/**
+	 * This enum defines all possible statuses a user can have.
+	 *
+	 * @since Envoy Common v0.2-alpha
+	 */
+	public static enum UserStatus {
 
-	private UserStatus status;
+		/**
+		 * select this, if a user is online and can be interacted with
+		 */
+		ONLINE,
+
+		/**
+		 * select this, if a user is online but unavailable at the moment (sudden
+		 * interruption)
+		 */
+		AWAY,
+
+		/**
+		 * select this, if a user is online but unavailable at the moment (polite way)
+		 */
+		BUSY,
+
+		/**
+		 * select this, if a user is offline
+		 */
+		OFFLINE;
+	}
 
 	private static final long serialVersionUID = 3530947374856708236L;
 
+	private final long id;
+
+	private final String name;
+
+	private UserStatus status;
+
 	/**
 	 * Initializes a {@link User}. The {@link UserStatus} is set to
 	 * {@link UserStatus#OFFLINE}.
-	 * 
+	 *
 	 * @param id   unique ID
 	 * @param name user name
 	 * @since Envoy Client v0.2-alpha
@@ -36,9 +66,6 @@ public class User implements Serializable {
 		status		= UserStatus.OFFLINE;
 	}
 
-	@Override
-	public String toString() { return String.format("User[id=%d,name=%s,status=%s]", id, name, status); }
-
 	/**
 	 * @return the ID of this {@link User}
 	 * @since Envoy Client v0.2-alpha
@@ -59,13 +86,12 @@ public class User implements Serializable {
 
 	/**
 	 * Sets the current status of this user
-	 * 
+	 *
 	 * @param status the status to set
 	 * @since Envoy Client v0.2-alpha
 	 */
 	public void setStatus(UserStatus status) { this.status = status; }
 
-	public static enum UserStatus {
-		ONLINE, AWAY, BUSY, OFFLINE;
-	}
+	@Override
+	public String toString() { return String.format("User[id=%d,name=%s,status=%s]", id, name, status); }
 }
\ No newline at end of file
diff --git a/src/main/java/envoy/exception/EnvoyException.java b/src/main/java/envoy/exception/EnvoyException.java
index 00f9946..650e1bb 100644
--- a/src/main/java/envoy/exception/EnvoyException.java
+++ b/src/main/java/envoy/exception/EnvoyException.java
@@ -1,20 +1,35 @@
-package envoy.exception;
-
-/**
- * Project: <strong>envoy-common</strong><br>
- * File: <strong>EnvoyException.java</strong><br>
- * Created: <strong>27 Oct 2019</strong><br>
- * 
- * @author Kai S. K. Engelbart
- * @since Envoy v0.1-alpha
- */
-public class EnvoyException extends Exception {
-
-	private static final long serialVersionUID = 2096147309395387479L;
-
-	public EnvoyException(String message, Throwable cause) { super(message, cause); }
-
-	public EnvoyException(String message) { super(message); }
-
-	public EnvoyException(Throwable cause) { super(cause); }
-}
+package envoy.exception;
+
+/**
+ * Project: <strong>envoy-common</strong><br>
+ * File: <strong>EnvoyException.java</strong><br>
+ * Created: <strong>27 Oct 2019</strong><br>
+ *
+ * @author Kai S. K. Engelbart
+ * @since Envoy v0.1-alpha
+ */
+public class EnvoyException extends Exception {
+
+	private static final long serialVersionUID = 2096147309395387479L;
+
+	/**
+	 * @param message the message to display once this Exception is thrown
+	 * @since Envoy Common v0.2-alpha
+	 */
+	public EnvoyException(String message) { super(message); }
+
+	/**
+	 * @param message the message to display once this Exception is thrown
+	 * @param cause   the {@link Throwable} which resulted in the throw of an
+	 *                EnvoyException
+	 * @since Envoy Common v0.2-alpha
+	 */
+	public EnvoyException(String message, Throwable cause) { super(message, cause); }
+
+	/**
+	 * @param cause the {@link Throwable} which resulted in the throw of an
+	 *              EnvoyException
+	 * @since Envoy Common v0.2-alpha
+	 */
+	public EnvoyException(Throwable cause) { super(cause); }
+}
diff --git a/src/main/java/envoy/util/SerializationUtils.java b/src/main/java/envoy/util/SerializationUtils.java
index dfd166b..c070733 100644
--- a/src/main/java/envoy/util/SerializationUtils.java
+++ b/src/main/java/envoy/util/SerializationUtils.java
@@ -11,28 +11,29 @@ import java.io.ObjectOutputStream;
 import java.io.OutputStream;
 import java.io.Serializable;
 
-import envoy.exception.EnvoyException;
-
 /**
  * Project: <strong>envoy-client</strong><br>
  * File: <strong>SerializationUtils.java</strong><br>
  * Created: <strong>23.12.2019</strong><br>
- * 
+ *
  * @author Kai S. K. Engelbart
  * @since Envoy Common v0.2-alpha
  */
 public class SerializationUtils {
 
-	private SerializationUtils() {}
+	private static byte[] intToBytes(int n) { return new byte[] { (byte) (n >>> 24), (byte) (n >>> 16), (byte) (n >>> 8), (byte) n }; }
 
 	/**
 	 * Deserializes an arbitrary {@link Serializable} object from a file.
-	 * 
+	 *
 	 * @param <T>             the type of the object to deserialize
-	 * @param file            the file deserialize from
+	 * @param file            the file to deserialize from
 	 * @param serializedClass the class of the object to deserialize
 	 * @return the deserialized object
-	 * @throws EnvoyException if an error occurred during deserialization
+	 * @throws IOException            if something failed while deserializing the
+	 *                                object
+	 * @throws ClassNotFoundException if the deserialized object can not be linked
+	 *                                to a class
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public static <T extends Serializable> T read(File file, Class<T> serializedClass) throws IOException, ClassNotFoundException {
@@ -40,6 +41,18 @@ public class SerializationUtils {
 		return read(new FileInputStream(file), serializedClass);
 	}
 
+	/**
+	 * @param <T>             the deserialized object
+	 * @param in              the {@link InputStream} of a serialized Object
+	 * @param serializedClass the object type to convert the deserialized object
+	 *                        into
+	 * @return the deserialized object
+	 * @throws IOException            if something failed while deserializing the
+	 *                                object
+	 * @throws ClassNotFoundException if the deserialized object can not be linked
+	 *                                to a class
+	 * @since Envoy Common v0.2-alpha
+	 */
 	public static <T extends Serializable> T read(InputStream in, Class<T> serializedClass) throws IOException, ClassNotFoundException {
 		try (ObjectInputStream oin = new ObjectInputStream(in)) {
 			return serializedClass.cast(oin.readObject());
@@ -48,7 +61,7 @@ public class SerializationUtils {
 
 	/**
 	 * Serializes an arbitrary object to a file.
-	 * 
+	 *
 	 * @param file the file to serialize to
 	 * @param obj  the object to serialize
 	 * @throws IOException if an error occurred during serialization
@@ -69,7 +82,7 @@ public class SerializationUtils {
 	/**
 	 * Serializes an object and writes it into an output stream preceded by 4 bytes
 	 * containing the number of serialized bytes.
-	 * 
+	 *
 	 * @param obj the object to serialize
 	 * @param out the output stream to serialize to
 	 * @throws IOException if an error occurred during serialization
@@ -90,5 +103,5 @@ public class SerializationUtils {
 		out.write(objBytes);
 	}
 
-	private static byte[] intToBytes(int n) { return new byte[] { (byte) (n >>> 24), (byte) (n >>> 16), (byte) (n >>> 8), (byte) n }; }
+	private SerializationUtils() {}
 }
\ No newline at end of file