采集程序的原理是什么？

Function getHTTPPage(url,language)
'On Error Resume Next
dim http
set http=Server.createobject("Microsoft.XMLHTTP")
Http.open "GET",url,false
Http.send()
if Http.readystate<>4 then
exit function
end if
getHTTPPage=bytesToBSTR(Http.responseBody,language)
set http=Nothing
If Err.number<>0 then
Response.Write "<p align='center'><font color='red'><b>服务器获取文件内容出错</b></font></p>"
Err.Clear
End If
End Function

Function BytesToBstr(body,Cset)
dim objstream
set objstream = Server.CreateObject("adodb.stream")
objstream.Type = 1
objstream.Mode =3
objstream.Open
objstream.Write body
objstream.Position = 0
objstream.Type = 2
objstream.Charset = Cset
BytesToBstr = objstream.ReadText
objstream.Close
set objstream = nothing
End Function

这是采集常用的两个函数。请问在采集的时候，程序是使用什么身份打开要采集的页面的？是使用哪个浏览器打开的吗？