diff --git a/src/Controller/InfoProviderController.php b/src/Controller/InfoProviderController.php
index 1236dba3..4c27dffe 100644
--- a/src/Controller/InfoProviderController.php
+++ b/src/Controller/InfoProviderController.php
@@ -29,7 +29,6 @@ use App\Form\InfoProviderSystem\PartSearchType;
 use App\Services\InfoProviderSystem\PartInfoRetriever;
 use App\Services\InfoProviderSystem\ProviderRegistry;
 use Doctrine\ORM\EntityManagerInterface;
-use Doctrine\ORM\QueryBuilder;
 use Psr\Log\LoggerInterface;
 use Symfony\Bridge\Doctrine\Attribute\MapEntity;
 use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
@@ -62,12 +61,26 @@ class InfoProviderController extends  AbstractController
         ]);
     }
 
+    /**
+     * Looks for parts in the local database that match the results from the info provider, so the user doesn't
+     * accidentally add a duplicate
+     *
+     * @param array $partsList Array of Arrays. Outer Array contains one entry per search result from the info Provider
+     * Inner array contains one entry "dto" for the dto from the info provider
+     * and one entry "localPart" where the local Part will be put if it exists
+     * Form: [["dto" => dto from provider, "localPart" => null]["dto" => dto from provider, "localPart" => null]]
+     * This function might modify the original array, not sure
+     * @return array Same format as the input array, but for parts that exist locally null will be replaced by a Part
+     */
     private function matchResultsToKnownParts(array $partsList): array
     {
+        //we need a manufacturer object to look for a manufacturer
         $manufacturerQb = $this->em->getRepository(Manufacturer::class)->createQueryBuilder("manufacturer");
         $manufacturerQb->where($manufacturerQb->expr()->like("LOWER(manufacturer.name)", "LOWER(:manufacturer_name)"));
 
 
+        //check if both manufacturer and Manufacturer part namber matches. If so, it must be the same part
+        //use LOWER to make the search independent of case
         $mpnQb = $this->em->getRepository(Part::class)->createQueryBuilder("part");
         $mpnQb->where($mpnQb->expr()->like("LOWER(part.manufacturer_product_number)", "LOWER(:mpn)"));
         $mpnQb->andWhere($mpnQb->expr()->eq("part.manufacturer", ":manufacturer"));
@@ -85,6 +98,7 @@ class InfoProviderController extends  AbstractController
             if(!$localParts) {
                 continue;
             }
+            //We only use the first matching part. If a user already has duplicate parts they will get a random one
             $partsList[$index]["localPart"] = $localParts[0];
         }
         return $partsList;
@@ -119,6 +133,9 @@ class InfoProviderController extends  AbstractController
                 //Log the exception
                 $exceptionLogger->error('Error during info provider search: ' . $e->getMessage(), ['exception' => $e]);
             }
+            // modify the array to an array of arrays that has a field for a matching local Part
+            // the advantage to use that format even when we don't look for local parts is that we
+            // always work with the same interface
             $results = array_map(function ($result) {return ["dto" => $result,"localPart" => null];}, $results);
             if(!$update_target) {
                 $results = $this->matchResultsToKnownParts($results);