Why is it important to use htmlspecialchars() when passing PHP output to HTML elements like input fields?

When passing PHP output to HTML elements like input fields, it is important to use htmlspecialchars() to prevent cross-site scripting (XSS) attacks. Without this function, malicious users could inject scripts into the input fields, leading to security vulnerabilities on the website. htmlspecialchars() escapes special characters like <, >, ", ', and & to their respective HTML entities, ensuring that the input is displayed as plain text and not executed as code. 

&lt;?php
$user_input = &quot;&lt;script&gt;alert(&#039;XSS attack&#039;);&lt;/script&gt;&quot;;
?&gt;
&lt;input type=&quot;text&quot; value=&quot;&lt;?php echo htmlspecialchars($user_input); ?&gt;&quot;&gt;

Keywords

htmlspecialchars PHP output HTML elements input fields security

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