what is the -i option when connecting to ssh?
Basically, it’s telling the SSH command to look at the key file you need for authentication on the destination server. If you use key authentication and were provided a certificate, this is where you want to specify it. If you use normal password auth, ignore that option.
For more use manpage of ssh for -i option explanation.
» ssh ↵
usage: ssh [-46AaCfGgKkMNnqsTtVvXxYy] …
[-i identity_file] …