Η ασφάλεια είναι κρίσιμη για κάθε web application. Ακολουθήστε αυτές τις best practices.

**Common Threats:**

**1. SQL Injection**
- Χρησιμοποιήστε prepared statements
- Input validation
- Parameterized queries

**2. XSS (Cross-Site Scripting)**
- Sanitize user input
- Content Security Policy
- Escape output

**3. CSRF (Cross-Site Request Forgery)**
- CSRF tokens
- SameSite cookies
- Verify origin

**4. Authentication Issues**
- Strong passwords
- Two-factor authentication
- Session management
- Password hashing (bcrypt)

**Security Best Practices:**

**1. HTTPS**
- Always use SSL/TLS
- Valid certificates
- HSTS headers

**2. Input Validation**
- Validate on server-side
- Sanitize all inputs
- Whitelist approach

**3. Error Handling**
- Don't expose sensitive info
- Generic error messages
- Proper logging

**4. Updates**
- Keep software updated
- Security patches
- Dependency management

**5. Access Control**
- Principle of least privilege
- Role-based access
- Regular audits

**Tools & Resources:**

- OWASP Top 10
- Security scanners
- Penetration testing
- Code reviews

**Συμπεράσματα**

Η ασφάλεια είναι ongoing process. Stay informed, update regularly, και test συνεχώς.