What is SQL injection and how does it work? What are some recommended methods to combat SQL injection? What is an XSS attack and how does it work? What are ways to prevent XSS attacks? What are some...

What is SQL injection and how does it work?  What are some recommended methods to combat SQL injection?

What is an XSS attack and how does it work? What are ways to prevent XSS attacks?

What are some ways to prevent authentication or session vulnerabilities.