A frame has many parameters that control its appearance and behavior. Just what parameters a frame has depends on what display mechanism it uses.
Frame parameters exist mostly for the sake of window systems. A
terminal frame has a few parameters, mostly for compatibility's sake;
only the height, width, name, title,
menu-bar-lines, buffer-list and buffer-predicate
parameters do something special. If the terminal supports colors, the
parameters foreground-color, background-color,
background-mode and display-type are also meaningful.
If the terminal supports frame transparency, the parameter
alpha is also meaningful.
You can use frame parameters to define frame-local bindings for variables. See Frame-Local Variables.