SSH's (secure shell) most common authentication mode is called "interactive keyboard password authentication", so called both because it is typically done via keyboard, and because openssh takes active measures to make sure that the password is, indeed, typed interactively by the keyboard. Sometimes, however, it is necessary to fool ssh into accepting an interactive password non-interactively. This is where sshpass comes in.
SECURITY NOTE: There is a reason openssh insists that passwords be typed interactively. Passwords are harder to store securely and to pass around securely between programs. If you