diff --git a/src/Composer/DependencyResolver/Package.php b/src/Composer/Package/BasePackage.php
similarity index 89%
rename from src/Composer/DependencyResolver/Package.php
rename to src/Composer/Package/BasePackage.php
index 7b3efab04..c64b67c61 100644
--- a/src/Composer/DependencyResolver/Package.php
+++ b/src/Composer/Package/BasePackage.php
@@ -9,46 +9,29 @@
  * file that was distributed with this source code.
  */
 
-namespace Composer\DependencyResolver;
+namespace Composer\Package;
 
 use Composer\DependencyResolver\RelationConstraint\RelationConstraintInterface;
 
 /**
+ * Base class for packages providing name storage and default match implementation
+ *
  * @author Nils Adermann <naderman@naderman.de>
  */
-abstract class Package
+abstract class Package implements PackageInterface
 {
     protected $name;
     protected $id;
 
-    static public $incremental_id = 1;
-
     /**
      * All descendents' constructors should call this parent constructor
      *
      * @param string $name The package's name
-     * @param int    $id   A positive unique id, zero to auto generate
      */
-    public function __construct($name, $id = 0)
+    public function __construct($name)
     {
         $this->name = $name;
 
-        if (!$id) {
-            $this->id = self::$incremental_id++;
-        } else {
-            $this->id = $id;
-            self::$incremental_id = $id + 1;
-        }
-    }
-
-    /**
-     * Returns the package's identifier
-     *
-     * @return int Package id - a unique positive number
-     */
-    public function getId()
-    {
-        return $this->id;
     }
 
     /**
diff --git a/src/Composer/DependencyResolver/MemoryPackage.php b/src/Composer/Package/MemoryPackage.php
similarity index 98%
rename from src/Composer/DependencyResolver/MemoryPackage.php
rename to src/Composer/Package/MemoryPackage.php
index 28496a8f3..f2af5bc48 100644
--- a/src/Composer/DependencyResolver/MemoryPackage.php
+++ b/src/Composer/Package/MemoryPackage.php
@@ -9,14 +9,14 @@
  * file that was distributed with this source code.
  */
 
-namespace Composer\DependencyResolver;
+namespace Composer\Package;
 
 /**
  * A package with setters for all members to create it dynamically in memory
  *
  * @author Nils Adermann <naderman@naderman.de>
  */
-class MemoryPackage extends Package
+class MemoryPackage extends BasePackage
 {
     protected $releaseType;
     protected $version;
diff --git a/src/Composer/Package/PackageInterface.php b/src/Composer/Package/PackageInterface.php
new file mode 100644
index 000000000..294fea6d0
--- /dev/null
+++ b/src/Composer/Package/PackageInterface.php
@@ -0,0 +1,116 @@
+<?php
+
+/*
+ * This file is part of Composer.
+ *
+ * (c) Nils Adermann <naderman@naderman.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Composer\Package;
+
+use Composer\DependencyResolver\RelationConstraint\RelationConstraintInterface;
+
+/**
+ * @author Nils Adermann <naderman@naderman.de>
+ */
+interface PackageInterface
+{
+    /**
+     * Returns the package's name without version info, thus not a unique identifier
+     *
+     * @return string package name
+     */
+    function getName();
+
+    /**
+     * Returns a set of names that could refer to this package
+     *
+     * No version or release type information should be included in any of the
+     * names. Provided or replaced package names need to be returned as well.
+     *
+     * @return array An array of strings refering to this package
+     */
+    function getNames();
+
+    /**
+     * Checks if the package matches the given constraint directly or through
+     * provided or replaced packages
+     *
+     * @param string                      $name       Name of the package to be matched
+     * @param RelationConstraintInterface $constraint The constraint to verify
+     * @return bool                                   Whether this package matches the name and constraint
+     */
+    function matches($name, RelationConstraintInterface $constraint);
+
+    /**
+     * Returns the release type of this package, e.g. stable or beta
+     *
+     * @return string The release type
+     */
+    function getReleaseType();
+
+    /**
+     * Returns the version of this package
+     *
+     * @return string version
+     */
+    function getVersion();
+
+    /**
+     * Returns a set of relations to packages which need to be installed before
+     * this package can be installed
+     *
+     * @return array An array of package relations defining required packages
+     */
+    function getRequires();
+
+    /**
+     * Returns a set of relations to packages which must not be installed at the
+     * same time as this package
+     *
+     * @return array An array of package relations defining conflicting packages
+     */
+    function getConflicts();
+
+    /**
+     * Returns a set of relations to virtual packages that are provided through
+     * this package
+     *
+     * @return array An array of package relations defining provided packages
+     */
+    function getProvides();
+
+    /**
+     * Returns a set of relations to packages which can alternatively be
+     * satisfied by installing this package
+     *
+     * @return array An array of package relations defining replaced packages
+     */
+    function getReplaces();
+
+    /**
+     * Returns a set of relations to packages which are recommended in
+     * combination with this package.
+     *
+     * @return array An array of package relations defining recommended packages
+     */
+    function getRecommends();
+
+    /**
+     * Returns a set of relations to packages which are suggested in combination
+     * with this package.
+     *
+     * @return array An array of package relations defining suggested packages
+     */
+    function getSuggests();
+
+    /**
+     * Converts the package into a readable and unique string
+     *
+     * @return string
+     */
+    function __toString();
+}