PHP is a widely-used programming language for server-side applications, but it's also vulnerable to various security threats, including cross-site scripting (XSS), SQL injection, cross-site request forgery (CSRF), session hijacking, buffer overflows, denial of service (DoS) and distributed denial of service (DDoS) attacks, password cracking, and man-in-the-middle (MitM) attacks. To improve PHP security, it's essential to incorporate vulnerability management tools like New Relic, follow secure coding practices, assume that attacks will happen and be prepared for them, use secure hosting, make systems fault-tolerant, conduct security audits, monitor activity in the application, set up alerts for critical performance thresholds, protect databases, and parameterize queries. By taking these steps, developers can reduce the risk of security breaches and protect their PHP applications from various types of attacks.