I'm no expert with websites but do manage a small charity site. I'd like to use the Calibri font that ships with certain Microsoft products but not everyone is going to have it installed on their system. If I specify Calibri in my stylesheet what happens on systems without this font installed, can I specify a replacent (Arial is pretty common) or will the users' individual browsers/settings pick a replacement or use their 'default' font?

Microsoft do supply a WEFT tool for font embedding, but it's old (and looks rather complicated) so I don't know whether it's worth exploring.

you basically specify a list and the browser starts at the left and works its way through until it finds one it recognizes:

ie:

p
{
font-family:"Times New Roman",Georgia,Serif;
}

info here

hope this makes sense.

Thanks for that, I'll have a play.

Don't do font-embedding – it doesn't work.

Put them in order of preference in the CSS as woffle says, finishing with sans-serif as the last option.

Make sure your layout actually works with all of them.