diff --git a/src/main/java/catering/inventory/InventoryController.java b/src/main/java/catering/inventory/InventoryController.java
index 9eaabbc..cd65123 100644
--- a/src/main/java/catering/inventory/InventoryController.java
+++ b/src/main/java/catering/inventory/InventoryController.java
@@ -53,6 +53,13 @@ class InventoryController {
 		this.cateringCatalog = cateringCatalog;
 	}
 
+	/**
+	 * Function to list all inventory products
+	 *
+	 * @param model the result of
+	 *              {@link org.springframework.ui.Model}
+	 * @return inventory.html
+	 */
 	@PreAuthorize("hasRole('ADMIN')")
 	@GetMapping("/inventory")
 	String list(Model model) {
@@ -61,6 +68,15 @@ class InventoryController {
 		return "inventory";
 	}
 
+	/**
+	 * Function to get data from form.
+	 *
+	 * @param model the result of
+	 * 	 *             {@link org.springframework.ui.Model}
+	 * @param pid type of
+	 * 	 * 				{@link org.salespointframework.catalog.Product}
+	 * @return 2nd edit() with new data of edit product
+	 */
 	@PreAuthorize("hasRole('ADMIN')")
 	@GetMapping("/inventory/edit/{pid}")
 	String edit(Model model, @PathVariable Product pid) {
@@ -77,6 +93,15 @@ class InventoryController {
 								.map(NumberValue::doubleValueExact)));
 	}
 
+	/**
+	 * Function to display the edit product.
+	 * @param model the result of
+	 * 	 *              {@link org.springframework.ui.Model}
+	 * @param pid type of
+	 * 	 * 				{@link org.salespointframework.catalog.Product}
+	 * @param form type of catering.InventoryMutateForm
+	 * @return inventory-mutate.html
+	 */
 	String edit(Model model, @PathVariable Product pid, InventoryMutateForm form) {
 		model.addAttribute("actionIsAdd", false);
 		model.addAttribute("form", form);
@@ -84,6 +109,18 @@ class InventoryController {
 		return "inventory-mutate";
 	}
 
+	/**
+	 * Function to set and save new data of edit product.
+	 *
+	 * @param form type of catering.InventoryMutateForm
+	 * @param result the result of
+	 * 	 * 	 *              {@link org.springframework.validation.Errors}
+	 * @param pid type of
+	 * 				{@link org.salespointframework.catalog.Product}
+	 * @param model the result of
+	 * 	 *              {@link org.springframework.ui.Model}
+	 * @return a redirect to inventory.html but with edit product
+	 */
 	@PreAuthorize("hasRole('ADMIN')")
 	@PostMapping("/inventory/edit/{pid}")
 	String edit(@Valid @ModelAttribute("form") InventoryMutateForm form, Errors result, @PathVariable Product pid, Model model) {
@@ -107,18 +144,42 @@ class InventoryController {
 		return "redirect:/inventory";
 	}
 
+	/**
+	 * Helper function for error handling in 3rd add().
+	 *
+	 * @param model the result of
+	 * 	 *              {@link org.springframework.ui.Model}
+	 * @return the 2nd add() with empty InventoryMutate Form
+	 */
 	@PreAuthorize("hasRole('ADMIN')")
 	@GetMapping("/inventory/add")
 	String add(Model model) {
 		return add(model, InventoryMutateForm.empty());
 	}
 
+	/**
+	 * Function to display the add product.
+	 *
+	 * @param model the result of
+	 * 	 *              {@link org.springframework.ui.Model}
+	 * @param form type of catering.InventoryMutateForm
+	 * @return inventory-mutate.html
+	 */
 	String add(Model model, InventoryMutateForm form) {
 		model.addAttribute("actionIsAdd", true);
 		model.addAttribute("form", form);
 		return "inventory-mutate";
 	}
 
+	/**
+	 *
+	 * @param form type of catering.InventoryMutateForm
+	 * @param result the result of
+	 * 	 *              {@link org.springframework.validation.Errors}
+	 * @param model the result of
+	 * 	 *              {@link org.springframework.ui.Model}
+	 * @return a redirect to inventory.html but with added product
+	 */
 	@PreAuthorize("hasRole('ADMIN')")
 	@PostMapping("/inventory/add")
 	String add(@Valid @ModelAttribute("form") InventoryMutateForm form, Errors result, Model model) {
@@ -134,6 +195,13 @@ class InventoryController {
 		return "redirect:/inventory";
 	}
 
+	/**
+	 * Function to delete one product in inventory.
+	 *
+	 * @param pid type of
+	 * 	 * 				{@link org.salespointframework.catalog.Product}
+	 * @return a redirect to inventory.html but without deleted product.
+	 */
 	@PreAuthorize("hasRole('ADMIN')")
 	@GetMapping("/inventory/delete/{pid}")
 	String delete(@PathVariable Product pid) {