difference between cookies generated by yahoo server and javaranch server

[samdeep aarzoo]

can anyone tell me in detail the cookie concept:
that is cookie generated by yahoo server . and
cookies generated by javaranch server.
as in java ranch server with same machine ,
there is no need to login again.

but in yahoo server we have to login again and again.
please help

[Annie Smith]

<short-reply> Yahoo expires its cookies after a stipulated period. </short-reply>
[ August 22, 2005: Message edited by: Annie Smith ]