HTML:  Fonts and sizes

<Font face="Arial">

This tag is used to insert different fonts into your web page.
<Font face> is used to insert a new font.
Arial is used as the font which is to be inserted.

If someone is using an old browser and you are using a new font on your page then either the page will not display correctly or the default font for that browser will be used (normally Times New Roman).

<Font size="4">

This tag is used to adjust the size of the font.
<Font size> is used to change the font size.
4 is the size of the font.

Font sizes are a bit different in HTML than in Word or other such programs.  Below is a list of HTML font sizes and Word font sizes.

1    8pt
2    10pt
3    12pt
4    14pt
5    18pt
6    24pt
7    36pt

You can still use decimals though, like 5.5 to get 21pt or 6.5 to get 30pt.  Size 3 is the normal font.