An SSH key is an access credential in the SSH protocol. We can login our server without password cause SSH key allow It. It is automated process for user and provide more secure our server.
Create SSH key in Linux or Mac
Run this command from your local server.
For more security run this command
ssh-keygen -b 4096
Run this command with login with your server
mkdir -p ~/.ssh && sudo chmod -R 700 ~/.ssh/
And run this command from your local server
In demo_user provide your username and 203.0.113.10 replace with your server IP.
Your server is more secured now.