What do < and > stand for?
<stands for the less-than sign:<>stands for the greater-than sign:>≤stands for the less-than or equals sign:≤≥stands for the greater-than or equals sign:≥
< Less than: <
> Greater than: >
They're used to explicitly define less than and greater than symbols. If one wanted to type out <html> and not have it be a tag in the HTML, one would use them. An alternate way is to wrap the <code> element around code to not run into that.
They can also be used to present mathematical operators.
<!ENTITY lt CDATA "<" -- less-than sign, U+003C ISOnum -->
<!ENTITY gt CDATA ">" -- greater-than sign, U+003E ISOnum -->
http://www.w3.org/TR/html4/sgml/entities.html