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title: "Ruby Compendium – The Core and the Standard Library"
content-type: page
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<p>By default, Ruby always loads its core classes and modules when a script is executed. This means that in all Ruby programs you can always instantiate core objects like:</p>
<ul>
	<li>Numbers (integers, floats)</li>
	<li>Strings</li>
	<li>Arrays</li>
	<li>Hashes</li>
	<li>Files</li>
	<li>Regular expressions</li>
	<li>Symbols</li>
	<li>Threads</li>
	<li>Times and dates</li>
	<li>&#8230;and many more.</li>
</ul>
<p>Most likely, this is not going to be enough. That&#8217;s when the Standard Library comes into play: it&#8217;s a large collection of internal libraries that ships with every Ruby implementations. There are libraries to connect to the Internet, to read/write to various file formats such as <span class="caps">CSV</span> or <span class="caps">YAML</span>, to work with files and paths, access system features, and so on.</p>
<p>Unlike core classes, standard libraries must be required specifically if needed, before they can be used.</p>
<aside class="box">
<div class="box-title">If you want to know more...</div>
<p>On core libraries and the Standard Library, checkout the official documentation:</p>
<ul>
	<li><a href="http://www.ruby-doc.org/core/">Core Reference</a></li>
	<li><a href="http://www.ruby-doc.org/stdlib/">Standard Library Reference</a></li>
</ul>
<p>Overwhelmed? Don&#8217;t know where to start? Familiarize yourself with the <a href="http://www.ruby-doc.org/core/classes/Enumerable.html">Enumerable</a> module; you won&#8217;t regret it!</p>

</aside>
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