Why do we use external stylesheets instead of inline or embedded styles?
It's more efficient to use external stylesheets. For example, a web developer can change one part of an external stylesheet and that change may affect an entire website spanning multiple pages. An equivalent alternation using inline or embedded styles may take considerable more effort and may need to be done page by page over an entire website.
What is the difference between SSH and FTP and why do we use each?
FTP stands for File Transfer Protocol, which was designed to transfer files from a remote location to a local computer or vice versa. SSH is a network protocol and stands for Secure Shell. SSH encrypts data before it is sent out. FTP is unsecure and SSH, by contrast, is very secure.