The document discusses the most common security threats faced by websites, including SQL injection, credential brute force attacks, cross-site scripting (XSS), and distributed denial of service (DDoS) attacks. It explains that websites store data on web servers accessed through the internet, making them vulnerable targets. The threats aim to steal information, abuse server resources, trick bots/crawlers, or exploit visitors. Proper web security is needed to prevent attacks and protect websites and their users.