font-weight attribute

Type:"normal", "bold"
Inherited:yes
Used By:All text elements
Default:"normal"
See:font-stretch font-style font

Set the weight of the font. Valid values are "bold" or "normal" - the other weights defined in CSS2 can be used, but are just synonyms for the most appopriate of these values.

The B tag is implemented like this in the default stylesheet

b { font-weight:bold; }