Filter() JQ. Для чего он в этом коде?

$(document).ready(function() { 
  $("#inputforsearch").on("keyup", function() { 
    var value = $(this).val().toLowerCase(); 
    $("#tabcontent tr").filter(function() { 
      $(this).toggle($(this).text().toLowerCase().indexOf(value) > -1); 
    }); 
  }); 
});

table { 
  text-align: left; 
  width: 100%; 
} 
 
tr:nth-child(odd) { 
  background-color: grey; 
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> 
<input type="text" placeholder="Search..." id="inputforsearch"> 
</br> 
<table> 
  <tr> 
    <th>Name</th> 
    <th>Surname</th> 
    <th>Email</th> 
  </tr> 
  <tbody id="tabcontent"> 
    <tr> 
      <td>Andrew</td> 
      <td>Yaremchuk</td> 
      <td>a.yaremchuk99@gmail.com</td> 
    </tr> 
    <tr> 
      <td>Vasya</td> 
      <td>Vakulenko</td> 
      <td>bastaakanoganno@mail.ru</td> 
    </tr> 
    <tr> 
      <td>Miron</td> 
      <td>Fedorow</td> 
      <td>norimyxxxo@boocking.com</td> 
    </tr> 
  </tbody> 
</table>