from the emacs package "auctex", among other places. Briefly,
In normal mode, F1 - F4 insert latex templates, unless they are
already there in the file. You have to provide these templates
yourself.
In insert mode, F1 - F5 enter environments such as \begin{..} \end{..}.
C-F1 - C-F5 alter existing environments.
(), $$, [], \[\], {}, \{\}, && are inserted in matching pairs.
Many Latex commands are bound to the ` key. (This comes from auctex).
For instance, \alpha is bound to `a, and \infty is bound to `8.
\frac{}{} is bound to `/ .
Menu items allow you to change or delete matching pairs of brackets,
as well as insert \left..\right automatically.
You can run Latex, start a viewer, and go to the position of the
latest Latex error.
The Alt key, followed by other keys, is used for inserting
\mathbf, \textbf, \sqrt, and so on.
Some macros are polymorphic. For instance, when preceded by bracket,
Alt-l will insert \left..\right around the brackets. Otherwise it
will insert \label{} and position the cursor in between the {}.
Likewise, Alt-c will produce \cite{} when preceded by a blank or at
the beginning of the line; but, for example, b followed by Alt-c
will produce \mathbf{B}.
There are "smart quotes". That is, typing " will produce a `` if there is
a space before the ", and will produce '' otherwise.
You can embrace the visual region with () by typing `(. This works
for other kinds of parentheses, too, as well as $$ and &&.
Long lines are automatically split up to keep $..$ (math expressions)
on the same line.
There are several abbreviations, such as \b for \bigskip.