XMLHttpRequest object enables brower like IE to make a http request without reloading the page using JavaScript.
example:
xmlhttp.open("GET", "test.txt",true);
xmlhttp.onreadystatechange=function() {
if (xmlhttp.readyState==4) {
alert(xmlhttp.responseText)
}
}
xmlhttp.send(null)
As of now, diff browers support this object differently.