PDF.js is an open-source JavaScript library developed by Mozilla that enables the rendering and viewing of PDF files directly within web browsers. By parsing and displaying PDFs using HTML5 and CSS, PDF.js eliminates the need for external plugins or native PDF viewers. This enhances both user experience and security, as it reduces the attack surface associated with traditional PDF readers, which are often targeted by cyber threats. In cybersecurity, using PDF.js can help mitigate risks such as malicious PDF exploits by sandboxing the rendering process within the browser environment. Its widespread adoption in web applications demonstrates its reliability and effectiveness for secure PDF handling.