Adding additional ssh-keys to your .ssh

Usually people will just create one key with just default command 

ssh-keygen 

get a public/private pair in (/Users/my_user/.ssh/id_rsa) and use that for anything, but there is much more to this then that. You can create many keys and use them for separate accounts and also automate that.

For example

ssh-keygen -f ~/.ssh/<username>  -C "your_email@example.com"

this will generate key with specific username and email you want and save it as such. Then you can add this info to config in ~/.ssh/config
and use it from there to connect which ssh key to use with which host like

Host github-org
    User git
    HostName github.com
    IdentityFile ~/.ssh/github.org.key

so you can have a key for each of the accounts/hosts you are using for some additional security and separation.
For some more info on that look here

https://nerderati.com/2011/03/17/simplify-your-life-with-an-ssh-config-…