Distributed Denial of Service (DDoS) attacks overwhelm your website with traffic, making it unavailable to users. To prevent DDoS attacks, choose a hosting provider with DDoS protection features such as traffic filtering and rate-limiting. Use a Content Delivery Network (CDN) to distribute traffic across multiple servers, reducing the load on your primary server. Additionally, enable firewalls and consider using a third-party security service that specializes in DDoS mitigation. It's also important to keep your website and server software up-to-date to ensure they are resilient against the latest attack vectors.