How to pass id from one page into another page in c#?

Question

Hai Friends,
I ve the "Travel.aspx" page like below fields

departuredate = textbox,
from = textbox,
to = textbox,
Mode= textbox
request_id visible="false" = textbox.

ADD(when i give the add above details ll be shown on gridview and default request_id ll generated)

save(after enter save these values ll be redirected into "HOME.aspx")

In Home.aspx
============

departuedate(link button) from to ll show on gridview.
when i press the link button redirect into "viewdetails.aspx".

the viewdetails .aspx is used to view what i saved on "travel.aspx"


here i wannna display values depends the request_id what i saved in "travel.aspx".
(i.e)get the request_id from travel.aspx pass into "viewdetails.aspx"


how to do that?