\documentclass{article}
\usepackage[utf8]{inputenc}

\begin{document}
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%Example of different font sizes and types
This is a simple example, {\tiny this will show different font sizes} and also \textsc{different font styles}. 
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\vspace{1cm}

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%Example of different font sizes and types
In this example the {\huge huge font size} is set and the {\footnotesize Foot note size also}. There's a fairly large set of font sizes.

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\vspace{1cm}

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%Example of different font sizes and types
Part of this text is written \textsl{in different font style} to highlight it.
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\vspace{1cm}

\textsc{Small capitals }
\\
\uppercase{upper all small letters}
\newline
First example, bold, italics and underline:

Some of the \textbf{greatest} discoveries in \underline{science} were made by \textbf{\textit{accident}}.

\vspace{1.5cm}

Example of italicized text: 

Some of the greatest discoveries in science were made by \textit{accident}.

\vspace{1.5cm}

Example of boldface text:

Some of the \textbf{greatest} discoveries in science were made by accident.

\vspace{1.5cm}

Example of underlined text:

Some of the greatest discoveries in \underline{science} were made by accident.

\vspace{1.5cm}

Example of emphasized text in different contexts:

Some of the greatest \emph{discoveries} in science were made by accident.

\textit{Some of the greatest \emph{discoveries} in science were made by accident.}

\textbf{Some of the greatest \emph{discoveries} in science were made by accident.}


\end{document}