A TeX-like syntax is used to specify special characters. Where possible,
these will be transformed into the native format of the exporter back-end.
Strings like \alpha will be exported as α in the HTML
output, and as $\alpha$ in the LaTeX output. Similarly,
\nbsp will become in HTML and ~ in LaTeX.
This applies for a large number of entities, with names taken from both HTML
and LaTeX, see the variable org-html-entities for the complete
list. If you are unsure about a name, use M-<TAB> for completion
after having types the backslash and maybe a few characters
(see Completion).
LaTeX fragments are converted into images for HTML export, and they are written literally into the LaTeX export. See also Embedded LaTeX.
Finally, ‘\-’ is treated as a shy hyphen, and ‘--’, ‘---’, and ‘...’ are all converted into special commands creating hyphens of different lengths or a compact set of dots.