求大神帮忙解释一下，（代码加粗的部分）自己取名字的这个el是个什么东西？有什么作用？
<body>
<table class="ui-table" width="800" id="studentInfo">
<caption><h2>XX中学学生资料</h2></caption>
<thead>
<tr>
<th style="width:45px">序号</th>
<th>姓名</th>
<th>学号</th>
<th>性别</th>
<th>年龄</th>
<th>所在班级</th>
<th>富二代</th>
</tr>
</thead>
<tbody>
<tr>
<td colspan="7">
<input type="button" value="加载资料" onclick="DisplayInfo()">
</td>
</tr>
</tbody>
</table>
<script>
var students = [
{"name": "张三", "id": "00145", "sex": "男", "age": "15", "class": "初一(3)班", "vip": "否"},
{"name": "李四", "id": "00110", "sex": "女", "age": "15", "class": "初二(2)班", "vip": "否"},
{"name": "王五", "id": "00251", "sex": "男", "age": "17", "class": "初一(4)班", "vip": "是"},
{"name": "赵六", "id": "00031", "sex": "女", "age": "16", "class": "初二(3)班", "vip": "否"},
{"name": "吴七", "id": "00009", "sex": "女", "age": "19", "class": "初三(6)班", "vip": "否"},
{"name": "候八", "id": "00352", "sex": "男", "age": "14", "class": "初一(2)班", "vip": "是"},
];
function DisplayInfo() {
var tbody = $("#studentInfo").find("tbody");
tbody.empty();
$.each(students,function(index, el) {
tbody.append(
"<tr><td>" + parseInt(index+1) + "</td><td>" +
el.name + "</td><td>" +
el.id + "</td><td>" +
el.sex + "</td><td>" +
el.age + "</td><td>" +
el.class + "</td><td>" +
el.vip + "</td></tr>");
});
}
</script>
</body>
