TeX provides almost any mathematical symbol you're likely to need.
Some, like + - = < > |
are obtained from the keyboard (the
first three can be used in any mode; the last three only in math mode).
Others are generated by LaTeX commands and can generally be used only in math mode. The following describe some of the useful symbols
\frac
generates fractions (math mode)
\sqrt
generates n-th root symbol
(math mode)
\stackrel
places one item above
another (math mode)
\boldmath
for a bold math font