how to use ssh without inputing a password

hi,
i am writing a script
ssh root@192.168.0.200 ls -l ,
ssh always prompts me to enter a password,
how to suppress it ,just like using rsh

thanks

Put your ssh public key to the remote host's authorized_keys file. See

http://acd.ucar.edu/~fredrick/mpark/ssh/rsa-unix.html

Also read

http://www.openssh.com/faq.html\#3.14

don't forget your private key on your client

http://www.openbsd.org/cgi-bin/man.cgi?query=ssh

I really appreciate all your help..... thanks a lot.