if you buy any nokia "smartphone"it has inbuilt pdf reader...you can download the screenshot of e-ticket and show it to tte,this is called vrs(virtual reservation slip)
or else since 1st february,for all the tickets booked on internet,irctc sends a detailed sms,which acts as ticket...
Please not that for both the case original id card is a must,but printout is not reqd if you show the sms/vrm...if you cant show any,rs.50 will be charged and an eft in lieu of ticket will be issued and the ticket prepared on board...
Irctc...
more... application need not be downloaded...it is just for information,and not for vrm/sms