Frage zu php

[H4wk3y3]

<form name="login" method="post" action="include.php?login=1">
 <input type="hidden" name="login_setcookie" value="1" />
 <input type="hidden" name="remove_path" value="path=start.php" />
  </td>
  </tr>
 <tr>
  <td>
  <input class="small" type="text" name="user" style="width: 100%" size="8" maxlength="50" value="Benutzername" onBlur="if (value =='') {value = 'Benutzername'}" onFocus="if (value == 'Benutzername') {value =''}" />
</td>
 </tr>
 <tr>
  <td>
  <input class="small" type="password" name="userpw" style="width: 100%" size="8" maxlength="50" value="passwort" onFocus="if (value == 'passwort') {value =''}"/>
</td>
 </tr>
 <tr>
  <td>
  <input class="small" type="submit" value="Login" />
  </td>
 </tr>
 </form>
 <tr>
  <td nowrap>
  <a class="navleft" href="include.php?path=login/subpass.php">Passwort vergessen?</a>
</td>
 </tr>
</td>
 </tr>
 <tr>
  <td class="navbgleft">
  <a class="navleft" href="include.php?path=login/register.php">Registrieren</a>

Könnt ihr mir erklären was das "?" bei z.B. <a class="navleft" href="include.php?path=login/register.php"> bedeutet???
ich hab gelesen und interessiere mich für Website bauen und möchte es gerne wissen.