References and Citations
Cross-referencing within your own document
See Figure~\ref{fig:diagram} on page~\pageref{fig:diagram}.\label{...} (set once, inside the figure/section/equation) and \ref{...} (used anywhere else) always stay correct even if you reorder sections — LaTeX renumbers them for you on the next compile. The ~ is a non-breaking space, so "Figure" and its number never get split across a line break.
A basic bibliography
\begin{thebibliography}{9}
\bibitem{smith2020} J. Smith, "A Paper Title," Journal Name, 2020.
\end{thebibliography}
As shown by Smith \cite{smith2020}...Why This Matters for Your Exams
Manually numbering figures/equations/citations by hand is exactly the kind of thing that breaks the moment you insert one more item earlier in the document -- \label/\ref/\cite exist so you never have to.