diff --git a/wiki/index.php b/wiki/index.php
index 000e940..034348c 100644
--- a/wiki/index.php
+++ b/wiki/index.php
@@ -8,17 +8,37 @@ include __DIR__."/../header.php";
 <p>here's the articles on our wiki:</p>
 <ul>
         <?php 
-              $article_to_title = [];
+              $category_to_articles = [];
               foreach (glob("source/*.md") as $file) {
                 $article = basename($file, ".md");
 		$title = preg_match("/title: (.*)/i", file_get_contents($file), $matches) ? $matches[1] : $article;
-                $article_to_title[$article] = $title;
+		$category = preg_match("/category: (.*)/i", file_get_contents($file), $matches) ? $matches[1] : 'default';
+		if (array_key_exists($category, $category_to_articles)) {
+			array_push($category_to_articles[$category], [$article, $title]);
+		} else {
+			$category_to_articles[$category] = [[$article, $title]];
+		}
+                ksort($category_to_articles);
               }
-              asort($article_to_title);
         ?>
-	<?php foreach ($article_to_title as $article => $title)	{ ?>
-		<li><a href="/wiki/<?=$article?>.html"><?=$title?></a></li>
-	<?php } ?>
+	<?php foreach ($category_to_articles as $category => $articles)	{ ?>
+		<li><?=$category?></li>
+			<ul>
+        <?php
+		$article_titles = [];
+		$article_names = [];
+		foreach ($articles as $article) {
+			array_push($article_names, $article[0]);
+                        array_push($article_titles, $article[1]);
+		}
+		$name_to_title = array_combine($article_names, $article_titles);
+                asort($name_to_title);
+		foreach ($name_to_title as $name => $title) { ?>
+                          <li><a href="/wiki/<?=$name?>.html"><?=$title?></a></li>
+	<?php   } ?>
+			</ul>
+
+        <?php } ?>
 </ul>
 
 <?php include __DIR__."/../footer.php";