Web Developer Dictionary

XML (eXtensible Markup Language) is a text format for structured data with custom tags. Older, stricter, and more verbose than JSON. Still widely used in enterprise systems, configuration files, RSS, and SOAP APIs. Structure Alice alice@example.com Advantages of XML over JSON Attributes (id="1") and element content — two distinct data types Namespaces — avoid name conflicts between schemas XSD schemas — stricter structural validation XSLT — transform XML into HTML/other XML PHP and XML $xml = simplexml_load_string($xmlString); echo $xml->user[0]->name; // Alice // Or via DOM $dom = new DOMDocument(); $dom->loadXML($xmlString); $nodes = $dom->getElementsByTagName('name');

XSS (Cross-Site Scripting) is the injection of malicious JavaScript into a page viewed by other users. The script runs in the victim's browser with the current site's privileges: it can steal cookies, capture keystrokes, and make requests on behalf of the user.TypesReflected — script in the URL, reflected in a single response. Requires tricking the victim into clicking a linkStored — script saved in the DB (comment, profile name) and shown to all visitors. Most dangerousDOM-based — DOM manipulation via JavaScript without server involvementDefenceOutput escaping — convert special HTML characters to entities: < → <. In PHP — htmlspecialchars(); in template engines — automatic escaping via double-brace syntaxContent Security Policy — an HTTP header that blocks inline scripts and scripts from untrusted domainsNever render raw user-supplied HTML without sanitisation through a dedicated library (HTML Purifier, etc.)