Using keys are more secure than using passwords for SSH, and easier since you don't need to keep entering the password to the remote machine.
Generating a Key
Basically just run the following command and hit enter 3 times to accept the defaults:
ssh-keygen -t rsa
Put Key on a Remote Machine
Run the following line to put the key on the remote machine. Be sure to change the REMOTE_USER and REMOTE_IP with your machine's info:
cat ~/.ssh/id_rsa.pub | ssh REMOTE_USER@REMOTE_IP "mkdir -p ~/.ssh && cat << ~/.ssh/authorized_keys"