LaTeX commands, packages, etc.

Packages

graphicx

incorporates (?) the features of psfig, epsfig

psfig, epsfig

amssymb

amsmath

provides align, flalign, gather, multline, split (alternatives to eqnarray)

colordvi

hyperref

theorem

showkeys

• displays the keys used for references and citations
• options: notref, notcite, color, final, draft
• example: \usepackage[notcite, notref]{showkeys} displays the keys only where they are defined (e.g., citations with \bibitem in the bibliography, equations with \label), not where they are quoted (with \cite or \ref)

refcheck

• check references (in figures, tables, equations, citations, etc)

Commands

Some commands might require a special package (most likely, amsmath or amssymb).

The (Info) mention means that you can find more about this in the Info pages of LaTeX.

\ensuremath{}

make sure the argument is always in math mode (even if not used that way)

\operatorname{}

produce Diff instead of Diff in math mode

displayed math equations

these are all environments, so should be used as \begin{...} and \end{...}

• aligned: produces more lines, the content of each being aligned with one or more &'s. Lines end with \\.
  It should be used within displayed math. It has a *-ed version.
• align: same as aligned, but equations can be numbered separately, and can continue from one page to the next.
  It has a *-ed version.
• split: to allow more lines; can align with one &.
  It should be used within displayed math.

ex, em, en, pt, in, cm

length units

\hfill, \hfil, \vfill, \vfil

fill empty horizontal or vertical space (Info)

\vspace{}, \hspace{}

skip the prescribed amount, vertically or horizontally (Info)

\bigskip, \medskip, \smallskip

vertical spacing (Info)

\sqrt{}

square -- or other -- root (e.g., \sqrt[3]{1+x^2} for cubic root) (Info)

\sloppy

makes TeX less fussy about line breaking (Info)

\fussy

opposite of \sloppy; it is the default (Info)

\pagestyle{} (see also \thispagestyle{})

changes the style from the current page on (Info)

\clearpage

ends the current page and causes all figures and tables that have so far appeared in the input to be printed (Info)

\textnormal{} (and \text{} if the amsmath package is used)

produce regular font (i.e., "text") while in mathematical mode. Spaces inside \text{} will not be ignored.
Example: $x^2\ge 0 \text{ for each } x\in \mathbb R$

\hrulefill

fill the rest of the line (or box) with a horizontal rule (Info)

\makebox[width][position]{text}

make a box with a specific content; if the width is not specified, it will be the width of the text (Info)
Examples: \makebox[1in]{\hrulefill} or \makebox[1in][l]{Name:}

\include{} and \input{}

read the content of the named file; \include allows for selective \input (Info)

\hookrightarrow

arrow used to denote bounded inclusion

\thebibliography

below is an example (refer to these items with \cite{Strassen67}, etc.) (Info)

\begin{thebibliography}{30}

\bibitem{Strassen67}
V.~Strassen. {Almost sure behavior of sums of independent random variables and
  martingales}. \emph{Proc. 5th Berkeley Symp. Math. Statist. Probab.},
  \textbf{2} (1967), 315--343.

\bibitem{Takahashi72}
S.~Takahashi. {Notes on the law of the iterated logarithm}. \emph{Studia Sci.
  Math. Hung.} \textbf{7} (1972), 21--24.

\end{thebibliography}