diff --git a/README.md b/README.md
index 0fbfa37..89d2bef 100644
--- a/README.md
+++ b/README.md
@@ -141,7 +141,8 @@ class TestHandler implements HandlerInterface
 }
 ```
 
-### 
+- All handlers must implement [HandlerInterface](src/Http/HandlerInterface.php)
+- A handler is a middleware, handler is just a fancy name given to it.
 
 ### [Example](example)
 
diff --git a/src/Http/Handler.php b/src/Http/Handler.php
index 547d521..c94d157 100644
--- a/src/Http/Handler.php
+++ b/src/Http/Handler.php
@@ -23,6 +23,12 @@ class Handler
     protected ResponseInterface $response;
 
 
+    /**
+     * Handler constructor.
+     * @param array $handlers
+     * @param ResponseInterface $response
+     * @throws InvalidArgumentException
+     */
     public function __construct(array $handlers, ResponseInterface $response)
     {
         $this->response = $response;
diff --git a/src/Http/HandlerInterface.php b/src/Http/HandlerInterface.php
index a4b252b..d6a82f3 100644
--- a/src/Http/HandlerInterface.php
+++ b/src/Http/HandlerInterface.php
@@ -5,12 +5,16 @@
 
 
 use Nette\Utils\JsonException;
+use Throwable;
 
 interface HandlerInterface
 {
     /**
+     * This serves like react's __invoke magic method,
+     * it will be called when request reach this handler
      * @param ResponseInterface $response
      * @throws JsonException
+     * @throws Throwable
      */
     public function handle(ResponseInterface $response): void;
 }
\ No newline at end of file
diff --git a/src/Http/Middleware.php b/src/Http/Middleware.php
index f56be33..b323179 100644
--- a/src/Http/Middleware.php
+++ b/src/Http/Middleware.php
@@ -18,6 +18,7 @@ class Middleware
     /**
      * Middleware constructor.
      * @param HandlerInterface ...$handler
+     * @throws InvalidArgumentException
      */
     public function __construct(...$handler)
     {
@@ -32,6 +33,7 @@ public function __construct(...$handler)
      * @param ServerRequestInterface $request
      * @return PromiseInterface
      * @throws JsonException
+     * @throws InvalidArgumentException
      */
     public function __invoke(ServerRequestInterface $request): PromiseInterface
     {