# Latex – 1 – Basics

I hope now you have installed Latex on your computer along with an editor (i.e. : TexStudio). So let’s put our hands on the very basics of Latex.

# Syntax

Since Latex uses a markup language to define the document structure, it consists of lots of similarities with markup languages. Latex translates your .tex file, which is a text file, into a high quality output file, similar to HTML.

Example source code would look like:

\documentclass[a4,12pt]{article}
\title{Introduction to Latex}
\author{Praneeth Nilanga Peiris}
\date{21 May 2014}
\begin{document}
\maketitle
Hello world! This is my first Latex document.
\end{document}

## Explanation

Each command starts with a ‘\‘ (back slash),with it’s name. Then the parameters are passed into that using one or more{}” (curly braces). In some cases, options to the tag (similar to attributes in HTML) are passed using ‘[]‘ (square brackets).

The document starts from \begin{document} and ends from \end{document} (similar to <HTML> and </HTML> in HTML). Hence, \begin{document} and \end{document} denotes the scope of the document.

There are some empty commands such as \maketitle, which doesn’t request any parameters (similar to <br/> in HTML)

## Spaces

Just like HTML, Latex ignores extra white spaces (spaces and tabs). But an empty line denotes a start of a new paragraph.

If you type this :

It does not matter whether you
enter one or several             spaces
after a word.

An empty line starts a new
paragraph.

The output still would be :

It does not matter whether you enter one or several spaces after a word.
An empty line starts a new paragraph.

## Reserved Characters

As every computer language, Latex also has a set of reserved characters. They are :

# \$ % ^ & _ { } ~ \

If you need those characters in your document, you should use a ‘\‘  prior to that. For example :

\# would output #

\% would output %

But you cannot use \\ to get \, since it denotes a line break. You have to use \blackslash for that purpose.

## Groups

A group is enclosed by ‘{‘ and ‘}’ where the range/scope of the commands put between those braces is limited to them.

{\bf
This is bold.
}
This is no longer bold.

## Environments

Environments in LaTeX have a role that is quite similar to commands, but they usually have effect on a wider part of the document. Their syntax is:

\begin{environment_name}
text to be influenced
\end{environment_name}

Example :

\begin{center}
Whatever you put here will be center aligned. It  can either be a text, image, table, figure etc.
\end{center}

## Commands

LaTeX commands are case sensitive, and take one of the following two formats:

• They start with a  ‘\’ and then have a name consisting of letters only. Command names are terminated by a space, a number or any other “non-letter”.
• They consist of a  ‘\’ and exactly one non-letter.

Some commands need an argument, which has to be given between { } after the command name. Some commands support optional parameters, which are added after the command name in []. The general syntax is:

\commandname[option1,option2,…]{argument1}{argument2}…

Most standard LaTeX commands have a switch equivalent. Switches have no arguments but apply on the rest of the scope (i.e. the current group or environment). A switch should (almost) never be called outside of any scope, otherwise it will apply on the rest of the document.

%\emph is a command with argument, \em is a switch.
\emph{emphasized text}, this part is normal % Correct
{\em emphasized text}, this part is normal % Correct

\em emphasized text, this part is normal % Incorrect
\em{emphasized text}, this part is normal % Incorrect

% is used to comment a single line. When a % is found, it ignores the rest of the current line, the line break, and all whitespace at the beginning of the next line.

Example :

This is an % stupid
% Better: instructive <----
example: Supercal %
ifragilist %
icexpialidocious

In order to use multi-line comments, you have to use a separate package called verbatim. You have to import that package by adding the following line before \begin{document} command. I will explain about packages in further articles.

\usepackage{verbatim}

Then you can use \begin{comment} and \end{comment} to insert multi-line comments as follows.

This is
\begin{comment}
something invisible, but
\end{comment}