What is meant by '->' in php and mysql

I am going through the example

     $conn = new mysqli($servername, $username, $password);
        if ($conn->connect_error) {
         die("Connection failed: " . $conn->connect_error);
       }

      $sql = "CREATE DATABASE myDB";
         if ($conn->query($sql) === TRUE) {
          echo "Database created successfully";

         } else {
          echo "Error creating database: " . $conn->error;
        }

What is the meaning of the symbol -> in the above example