However, a problem arises with fonts, which can be particularly irritating if you are trying to lay out a page so that the fonts look right against the graphics. On a Macintosh monitor, the notional resolution is 72 dots-per -inch (dpi), so that a graphic 72 pixels wide would notionally be 1 inch wide - though obviously the actual size would depend on the individual monitor. However it will always print one inch wide.
But on a Windows monitor the resolution is (usually) 96 dpi. This means that though the picture is still 72 pixels wide, it will print at 0.75 inches.
Font size is described in 'points', a point being one-seventy-second of an inch (this standard was set long before computers were invented). The situation is slightly more complicated than it sounds, since different fonts at the same size may look to be a quite different size, depending on the design, so for the purposes of this discussion we will assume that we are always talking about one particular font.
Let us pretend that we have a 12 point font containing a character which is actually the full 12 points high (because, for example, the lower-case o is nothing like that). It will print, even in pre-computer technology, at twelve-seventy-seconds, or one-sixth, of an inch.
On a Macintosh it will be 12 pixels high on the monitor and will of course print at one-sixth of an inch high.
On a Windows monitor with 96 dpi resolution it will still need to be one-sixth of an inch high (and print as such) so it will be one-sixth of 96 pixels high, or 16 pixels.
So if we have a graphic 12 pixels high and this font character at 12 point, they will appear the same size on a Macintosh monitor, but on a Windows monitor the font character will be one-third higher than the graphic.