I am using emacs 23.3. I need to change the font size and font type, can anyone help me?
If you use Linux/X11, you may need to set this in ~/.Xdefaults. I
have set the font there since the other answers here have no effect.
I'm able to see available font settings by running in Emacs:
helm-select-xfont
Then I start typing Conso and I see entries like:
-Consolas-normal-normal-normal-*-*-*-*-*-m-0-iso10646-1
...
So then I put it into ~/.Xdefaults, setting size 12 as:
Emacs.font: xft:-*-Consolas-normal-normal-normal-*-12-*-*-*-m-0-iso10646-1
and restart Emacs.
You can use the menu bar. Go to Options->Set Default Font....
After you choose a font, don't forget to press Options->Save Options—otherwise your new font will not be saved after you close Emacs.