Now days you might working for more than 1 companies or you will might be having your personal GITHUB account and company GITHUB account where you want to manage multiple GIT key pairs in your computer without affecting the other accounts. I hope you know how to generate the SSH key pairs with ssh-keygen in your computer.
If you have given any other name in the place of id_rsa then replace in the following: Now you have added the SSH keys for your company and personal account.
You need to set company and personal project keys else when you commit in you personal project you might see company username in commit history instead of personal name.
You can configure this for your project level with the following , here you can add your personal email and name.