SFTP (Secure File Transfer Protocol) is the transfer protocol to view and transfer files over SSH. SFTP works the same as FTP but is encrypted.
SFTP Advantages
Encrypted
Nothing extra to install (such as FTP server)
Works like any other FTP server
Compatible with the popular clients such as Filezilla and WinSCP
You can login to any SSH accessable Linux user.
How to use SFTP
Connect like any FTP except it uses the port (default 22)
Use your linux username / password
You might need to set protocol to SFTP in your FTP client.
Bad practice to avoid
By all means, you should never
1.
Connect to a server as root.
2.
Use FTP if SFTP is available.
Root login to an FTP
Here is why you shouldn't
By logging in as root, you might accidentally remove essential system files or put useless files into the wrong place and mess up with your system.
But even more annoying, any file you'll write will belong to root, and the user won't be able to either read, change, or execute writtent files as root.
FTP is an unencrypted protocol, therefore it is very unsecure to edit sensitive files using it.
How to operate without root FTP login ?
If you need to edit system config files, then do like everyone else : use an SSH text editor like "nano" or "vi".
Set your FTP so that you can login as users with a valid shell from the machine. Eventually, disable root FTP login.