Using Input/Include Commands
Each chapter or section in the document is referenced in a root file using either the \input or the \include command. This has the added advantage of listing all the external chapter files in the main file and then by either commenting or uncomment them, include or exclude them to the output stream when generating a LaTex document.
Note: For more information about input and include and their differences, see this topic on tex.stackexchange.com: When should I use input vs. include.
Using the input Command
The command \input{filename} imports a file such as filename.tex into the target file. It’s equivalent to typing the content of filename.tex into the current file at the location of the \input line.
Additionally, the order in which the files are listed determines the order of the chapters or sections.
\input{filename}
For example, the following list of chapters use the \input command to insert the files into the typesetting stream for output.
%% Chapters inputs
\input{MANUAL/manual-ch01-preface.tex}
\input{MANUAL/manual-ch02-overview.tex}
\input{MANUAL/manual-ch03.tex}
\input{MANUAL/manual-ch04.tex}
\input{MANUAL/manual-ch05.tex}
\input{MANUAL/manual-ch06.tex}
\input{MANUAL/manual-ch07.tex}
\input{MANUAL/manual-ch08.tex}
\input{MANUAL/manual-ch09.tex}
\input{MANUAL/manual-ch10.tex}
\input{MANUAL/manual-ch11-troubleshooting.tex}
\input{MANUAL/manual-ch12-tutorials.tex}
\input{MANUAL/manual-ch13-faq.tex}
\input{MANUAL/manual-ch14-release-notes}
For most purposes, the \input command is sufficient. If you want more control over placement of content, then use the \include command.
Using the include Command
The command include{filename} adds a \clearpage before and after the insertion of the LaTex file into the typesetting stream. This results in the chapter starting on a new page.
\include{filename}
For example, the following list of chapters use the \include command to insert the files into the typesetting stream for output but all starting on a new page in the document.
\include{tex/preface}
\include{tex/intro}
\include{tex/chap01}
\include{tex/chap02}
\include{tex/summary}