diff --git a/AbstractBrowser.php b/AbstractBrowser.php
index f8c89871..977dd28a 100644
--- a/AbstractBrowser.php
+++ b/AbstractBrowser.php
@@ -111,7 +111,7 @@ public function getMaxRedirects()
      */
     public function insulate(bool $insulated = true)
     {
-        if ($insulated && !class_exists('Symfony\\Component\\Process\\Process')) {
+        if ($insulated && !class_exists(\Symfony\Component\Process\Process::class)) {
             throw new \LogicException('Unable to isolate requests as the Symfony Process Component is not installed.');
         }
 
@@ -147,7 +147,7 @@ public function setServerParameter(string $key, string $value)
      */
     public function getServerParameter(string $key, $default = '')
     {
-        return isset($this->server[$key]) ? $this->server[$key] : $default;
+        return $this->server[$key] ?? $default;
     }
 
     public function xmlHttpRequest(string $method, string $uri, array $parameters = [], array $files = [], array $server = [], string $content = null, bool $changeHistory = true): Crawler
@@ -503,7 +503,7 @@ protected function filterResponse($response)
      */
     protected function createCrawlerFromContent(string $uri, string $content, string $type)
     {
-        if (!class_exists('Symfony\Component\DomCrawler\Crawler')) {
+        if (!class_exists(Crawler::class)) {
             return null;
         }
 
@@ -647,7 +647,7 @@ protected function getAbsoluteUri(string $uri)
         } else {
             $currentUri = sprintf('http%s://%s/',
                 isset($this->server['HTTPS']) ? 's' : '',
-                isset($this->server['HTTP_HOST']) ? $this->server['HTTP_HOST'] : 'localhost'
+                $this->server['HTTP_HOST'] ?? 'localhost'
             );
         }
 
diff --git a/Cookie.php b/Cookie.php
index c24661de..a416966a 100644
--- a/Cookie.php
+++ b/Cookie.php
@@ -22,7 +22,7 @@ class Cookie
      * Handles dates as defined by RFC 2616 section 3.3.1, and also some other
      * non-standard, but common formats.
      */
-    private static $dateFormats = [
+    private const DATE_FORMATS = [
         'D, d M Y H:i:s T',
         'D, d-M-y H:i:s T',
         'D, d-M-Y H:i:s T',
@@ -92,7 +92,7 @@ public function __toString()
 
         if (null !== $this->expires) {
             $dateTime = \DateTime::createFromFormat('U', $this->expires, new \DateTimeZone('GMT'));
-            $cookie .= '; expires='.str_replace('+0000', '', $dateTime->format(self::$dateFormats[0]));
+            $cookie .= '; expires='.str_replace('+0000', '', $dateTime->format(self::DATE_FORMATS[0]));
         }
 
         if ('' !== $this->domain) {
@@ -205,7 +205,7 @@ private static function parseDate(string $dateValue): ?string
             $dateValue = substr($dateValue, 1, -1);
         }
 
-        foreach (self::$dateFormats as $dateFormat) {
+        foreach (self::DATE_FORMATS as $dateFormat) {
             if (false !== $date = \DateTime::createFromFormat($dateFormat, $dateValue, new \DateTimeZone('GMT'))) {
                 return $date->format('U');
             }
diff --git a/LICENSE b/LICENSE
index 9e936ec0..9ff2d0d6 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright (c) 2004-2020 Fabien Potencier
+Copyright (c) 2004-2021 Fabien Potencier
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/Tests/AbstractBrowserTest.php b/Tests/AbstractBrowserTest.php
index 4292cd55..b71f5454 100644
--- a/Tests/AbstractBrowserTest.php
+++ b/Tests/AbstractBrowserTest.php
@@ -13,7 +13,9 @@
 
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\BrowserKit\CookieJar;
+use Symfony\Component\BrowserKit\Exception\BadMethodCallException;
 use Symfony\Component\BrowserKit\History;
+use Symfony\Component\BrowserKit\Request;
 use Symfony\Component\BrowserKit\Response;
 
 class AbstractBrowserTest extends TestCase
@@ -45,7 +47,7 @@ public function testGetRequest()
 
     public function testGetRequestNull()
     {
-        $this->expectException('Symfony\Component\BrowserKit\Exception\BadMethodCallException');
+        $this->expectException(BadMethodCallException::class);
         $this->expectExceptionMessage('The "request()" method must be called before "Symfony\\Component\\BrowserKit\\AbstractBrowser::getRequest()".');
 
         $client = $this->getBrowser();
@@ -77,12 +79,12 @@ public function testGetResponse()
         $client->request('GET', 'http://example.com/');
 
         $this->assertSame('foo', $client->getResponse()->getContent(), '->getCrawler() returns the Response of the last request');
-        $this->assertInstanceOf('Symfony\Component\BrowserKit\Response', $client->getResponse(), '->getCrawler() returns the Response of the last request');
+        $this->assertInstanceOf(Response::class, $client->getResponse(), '->getCrawler() returns the Response of the last request');
     }
 
     public function testGetResponseNull()
     {
-        $this->expectException('Symfony\Component\BrowserKit\Exception\BadMethodCallException');
+        $this->expectException(BadMethodCallException::class);
         $this->expectExceptionMessage('The "request()" method must be called before "Symfony\\Component\\BrowserKit\\AbstractBrowser::getResponse()".');
 
         $client = $this->getBrowser();
@@ -91,7 +93,7 @@ public function testGetResponseNull()
 
     public function testGetInternalResponseNull()
     {
-        $this->expectException('Symfony\Component\BrowserKit\Exception\BadMethodCallException');
+        $this->expectException(BadMethodCallException::class);
         $this->expectExceptionMessage('The "request()" method must be called before "Symfony\\Component\\BrowserKit\\AbstractBrowser::getInternalResponse()".');
 
         $client = $this->getBrowser();
@@ -118,7 +120,7 @@ public function testGetCrawler()
 
     public function testGetCrawlerNull()
     {
-        $this->expectException('Symfony\Component\BrowserKit\Exception\BadMethodCallException');
+        $this->expectException(BadMethodCallException::class);
         $this->expectExceptionMessage('The "request()" method must be called before "Symfony\\Component\\BrowserKit\\AbstractBrowser::getCrawler()".');
 
         $client = $this->getBrowser();
@@ -285,7 +287,7 @@ public function testClickLinkNotFound()
             $client->clickLink('foo');
             $this->fail('->clickLink() throws a \InvalidArgumentException if the link could not be found');
         } catch (\Exception $e) {
-            $this->assertInstanceOf('InvalidArgumentException', $e, '->clickLink() throws a \InvalidArgumentException if the link could not be found');
+            $this->assertInstanceOf(\InvalidArgumentException::class, $e, '->clickLink() throws a \InvalidArgumentException if the link could not be found');
         }
     }
 
@@ -344,7 +346,7 @@ public function testSubmitFormNotFound()
             ], 'POST');
             $this->fail('->submitForm() throws a \InvalidArgumentException if the form could not be found');
         } catch (\Exception $e) {
-            $this->assertInstanceOf('InvalidArgumentException', $e, '->submitForm() throws a \InvalidArgumentException if the form could not be found');
+            $this->assertInstanceOf(\InvalidArgumentException::class, $e, '->submitForm() throws a \InvalidArgumentException if the form could not be found');
         }
     }
 
@@ -395,7 +397,7 @@ public function testFollowRedirect()
             $client->followRedirect();
             $this->fail('->followRedirect() throws a \LogicException if the request was not redirected');
         } catch (\Exception $e) {
-            $this->assertInstanceOf('LogicException', $e, '->followRedirect() throws a \LogicException if the request was not redirected');
+            $this->assertInstanceOf(\LogicException::class, $e, '->followRedirect() throws a \LogicException if the request was not redirected');
         }
 
         $client->setNextResponse(new Response('', 302, ['Location' => 'http://www.example.com/redirected']));
@@ -425,7 +427,7 @@ public function testFollowRedirect()
             $client->followRedirect();
             $this->fail('->followRedirect() throws a \LogicException if the request did not respond with 30x HTTP Code');
         } catch (\Exception $e) {
-            $this->assertInstanceOf('LogicException', $e, '->followRedirect() throws a \LogicException if the request did not respond with 30x HTTP Code');
+            $this->assertInstanceOf(\LogicException::class, $e, '->followRedirect() throws a \LogicException if the request did not respond with 30x HTTP Code');
         }
     }
 
@@ -455,7 +457,7 @@ public function testFollowRedirectWithMaxRedirects()
             $client->followRedirect();
             $this->fail('->followRedirect() throws a \LogicException if the request was redirected and limit of redirections was reached');
         } catch (\Exception $e) {
-            $this->assertInstanceOf('LogicException', $e, '->followRedirect() throws a \LogicException if the request was redirected and limit of redirections was reached');
+            $this->assertInstanceOf(\LogicException::class, $e, '->followRedirect() throws a \LogicException if the request was redirected and limit of redirections was reached');
         }
 
         $client->setNextResponse(new Response('', 302, ['Location' => 'http://www.example.com/redirected']));
@@ -738,7 +740,7 @@ public function testInsulatedRequests()
             $client->request('GET', 'http://www.example.com/foo/foobar');
             $this->fail('->request() throws a \RuntimeException if the script has an error');
         } catch (\Exception $e) {
-            $this->assertInstanceOf('RuntimeException', $e, '->request() throws a \RuntimeException if the script has an error');
+            $this->assertInstanceOf(\RuntimeException::class, $e, '->request() throws a \RuntimeException if the script has an error');
         }
     }
 
@@ -826,12 +828,12 @@ public function testInternalRequest()
             'NEW_SERVER_KEY' => 'new-server-key-value',
         ]);
 
-        $this->assertInstanceOf('Symfony\Component\BrowserKit\Request', $client->getInternalRequest());
+        $this->assertInstanceOf(Request::class, $client->getInternalRequest());
     }
 
     public function testInternalRequestNull()
     {
-        $this->expectException('Symfony\Component\BrowserKit\Exception\BadMethodCallException');
+        $this->expectException(BadMethodCallException::class);
         $this->expectExceptionMessage('The "request()" method must be called before "Symfony\\Component\\BrowserKit\\AbstractBrowser::getInternalRequest()".');
 
         $client = $this->getBrowser();
diff --git a/Tests/CookieJarTest.php b/Tests/CookieJarTest.php
index d88f0234..414f5dc6 100644
--- a/Tests/CookieJarTest.php
+++ b/Tests/CookieJarTest.php
@@ -77,8 +77,8 @@ public function testUpdateFromSetCookie()
         $cookieJar->set(new Cookie('bar', 'bar'));
         $cookieJar->updateFromSetCookie($setCookies);
 
-        $this->assertInstanceOf('Symfony\Component\BrowserKit\Cookie', $cookieJar->get('foo'));
-        $this->assertInstanceOf('Symfony\Component\BrowserKit\Cookie', $cookieJar->get('bar'));
+        $this->assertInstanceOf(Cookie::class, $cookieJar->get('foo'));
+        $this->assertInstanceOf(Cookie::class, $cookieJar->get('bar'));
         $this->assertEquals('foo', $cookieJar->get('foo')->getValue(), '->updateFromSetCookie() updates cookies from a Set-Cookie header');
         $this->assertEquals('bar', $cookieJar->get('bar')->getValue(), '->updateFromSetCookie() keeps existing cookies');
     }
@@ -103,9 +103,9 @@ public function testUpdateFromSetCookieWithMultipleCookies()
         $barCookie = $cookieJar->get('bar', '/', '.blog.symfony.com');
         $phpCookie = $cookieJar->get('PHPSESSID');
 
-        $this->assertInstanceOf('Symfony\Component\BrowserKit\Cookie', $fooCookie);
-        $this->assertInstanceOf('Symfony\Component\BrowserKit\Cookie', $barCookie);
-        $this->assertInstanceOf('Symfony\Component\BrowserKit\Cookie', $phpCookie);
+        $this->assertInstanceOf(Cookie::class, $fooCookie);
+        $this->assertInstanceOf(Cookie::class, $barCookie);
+        $this->assertInstanceOf(Cookie::class, $phpCookie);
         $this->assertEquals('foo', $fooCookie->getValue());
         $this->assertEquals('bar', $barCookie->getValue());
         $this->assertEquals('id', $phpCookie->getValue());
diff --git a/Tests/CookieTest.php b/Tests/CookieTest.php
index 5f99eb11..a9b34139 100644
--- a/Tests/CookieTest.php
+++ b/Tests/CookieTest.php
@@ -104,7 +104,7 @@ public function testFromStringWithUrl()
 
     public function testFromStringThrowsAnExceptionIfCookieIsNotValid()
     {
-        $this->expectException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         Cookie::fromString('foo');
     }
 
@@ -117,7 +117,7 @@ public function testFromStringIgnoresInvalidExpiresDate()
 
     public function testFromStringThrowsAnExceptionIfUrlIsNotValid()
     {
-        $this->expectException('InvalidArgumentException');
+        $this->expectException(\InvalidArgumentException::class);
         Cookie::fromString('foo=bar', 'foobar');
     }
 
@@ -200,7 +200,7 @@ public function testIsExpired()
 
     public function testConstructException()
     {
-        $this->expectException('UnexpectedValueException');
+        $this->expectException(\UnexpectedValueException::class);
         $this->expectExceptionMessage('The cookie expiration time "string" is not valid.');
         new Cookie('foo', 'bar', 'string');
     }
diff --git a/Tests/HistoryTest.php b/Tests/HistoryTest.php
index aa09b05b..8f3cfae1 100644
--- a/Tests/HistoryTest.php
+++ b/Tests/HistoryTest.php
@@ -55,7 +55,7 @@ public function testCurrent()
             $history->current();
             $this->fail('->current() throws a \LogicException if the history is empty');
         } catch (\Exception $e) {
-            $this->assertInstanceOf('LogicException', $e, '->current() throws a \LogicException if the history is empty');
+            $this->assertInstanceOf(\LogicException::class, $e, '->current() throws a \LogicException if the history is empty');
         }
 
         $history->add(new Request('http://www.example.com/', 'get'));
@@ -72,7 +72,7 @@ public function testBack()
             $history->back();
             $this->fail('->back() throws a \LogicException if the history is already on the first page');
         } catch (\Exception $e) {
-            $this->assertInstanceOf('LogicException', $e, '->current() throws a \LogicException if the history is already on the first page');
+            $this->assertInstanceOf(\LogicException::class, $e, '->current() throws a \LogicException if the history is already on the first page');
         }
 
         $history->add(new Request('http://www.example1.com/', 'get'));
@@ -91,7 +91,7 @@ public function testForward()
             $history->forward();
             $this->fail('->forward() throws a \LogicException if the history is already on the last page');
         } catch (\Exception $e) {
-            $this->assertInstanceOf('LogicException', $e, '->forward() throws a \LogicException if the history is already on the last page');
+            $this->assertInstanceOf(\LogicException::class, $e, '->forward() throws a \LogicException if the history is already on the last page');
         }
 
         $history->back();
diff --git a/Tests/HttpBrowserTest.php b/Tests/HttpBrowserTest.php
index 1397d9b1..4cd44aff 100644
--- a/Tests/HttpBrowserTest.php
+++ b/Tests/HttpBrowserTest.php
@@ -73,7 +73,7 @@ public function testMultiPartRequestWithSingleFile()
             ->method('request')
             ->with('POST', 'http://example.com/', $this->callback(function ($options) {
                 $this->assertStringContainsString('Content-Type: multipart/form-data', implode('', $options['headers']));
-                $this->assertInstanceOf('\Generator', $options['body']);
+                $this->assertInstanceOf(\Generator::class, $options['body']);
                 $this->assertStringContainsString('my_file', implode('', iterator_to_array($options['body'])));
 
                 return true;
@@ -183,7 +183,7 @@ protected function expectClientToSendRequestWithFiles(HttpClientInterface $clien
             ->method('request')
             ->with('POST', 'http://example.com/', $this->callback(function ($options) use ($fileContents) {
                 $this->assertStringContainsString('Content-Type: multipart/form-data', implode('', $options['headers']));
-                $this->assertInstanceOf('\Generator', $options['body']);
+                $this->assertInstanceOf(\Generator::class, $options['body']);
                 $body = implode('', iterator_to_array($options['body'], false));
                 foreach ($fileContents as $content) {
                     $this->assertStringContainsString($content, $body);
@@ -201,7 +201,7 @@ protected function expectClientToNotSendRequestWithFiles(HttpClientInterface $cl
             ->method('request')
             ->with('POST', 'http://example.com/', $this->callback(function ($options) use ($fileContents) {
                 $this->assertStringContainsString('Content-Type: multipart/form-data', implode('', $options['headers']));
-                $this->assertInstanceOf('\Generator', $options['body']);
+                $this->assertInstanceOf(\Generator::class, $options['body']);
                 $body = implode('', iterator_to_array($options['body'], false));
                 foreach ($fileContents as $content) {
                     $this->assertStringNotContainsString($content, $body);
diff --git a/Tests/RequestTest.php b/Tests/RequestTest.php
index 5d7c7d6b..a7327b0f 100644
--- a/Tests/RequestTest.php
+++ b/Tests/RequestTest.php
@@ -52,7 +52,7 @@ public function testGetServer()
         $this->assertEquals(['foo' => 'bar'], $request->getServer(), '->getServer() returns the server parameters of the request');
     }
 
-    public function testAllParameterValuesAreConvertedToString(): void
+    public function testAllParameterValuesAreConvertedToString()
     {
         $parameters = [
             'foo' => 1,
diff --git a/Tests/TestClient.php b/Tests/TestClient.php
index 0efa48b9..64e4937e 100644
--- a/Tests/TestClient.php
+++ b/Tests/TestClient.php
@@ -43,7 +43,7 @@ protected function doRequest($request): Response
 
     protected function getScript($request)
     {
-        $r = new \ReflectionClass('Symfony\Component\BrowserKit\Response');
+        $r = new \ReflectionClass(Response::class);
         $path = $r->getFileName();
 
         return <<<EOF
diff --git a/Tests/TestHttpClient.php b/Tests/TestHttpClient.php
index cbdc2ae1..377f5dc1 100644
--- a/Tests/TestHttpClient.php
+++ b/Tests/TestHttpClient.php
@@ -66,7 +66,7 @@ protected function doRequest($request): Response
 
     protected function getScript($request)
     {
-        $r = new \ReflectionClass('Symfony\Component\BrowserKit\Response');
+        $r = new \ReflectionClass(Response::class);
         $path = $r->getFileName();
 
         return <<<EOF
diff --git a/composer.json b/composer.json
index e2165368..239b8faa 100644
--- a/composer.json
+++ b/composer.json
@@ -1,7 +1,7 @@
 {
     "name": "symfony/browser-kit",
     "type": "library",
-    "description": "Symfony BrowserKit Component",
+    "description": "Simulates the behavior of a web browser, allowing you to make requests, click on links and submit forms programmatically",
     "keywords": [],
     "homepage": "https://symfony.com",
     "license": "MIT",