What are the repercussions of a DDoS attack on a website? [closed]

Question

First of all, I'd like to know what exactly a DDoS attack is- my understanding is that it's a collection of infected or "zombie" computers, all controlled by a central computer, with the intent of overloading the website, and making it inaccessible and / or slowing the service down to 90's dial up levels (a.k.a. unusable).

How can one prevent it? I understand that those annoying CAPTCHAs are used, but is there actually a way to prevent one manually?

How well do third-party security services, such as cloudflare or fire eye, work? Are there ways to beat them?

What are the repercussions of a DDoS attack? If a website is DDoS'd, are passwords / credit card / bank data stored in the database compromised? Are certain pieces of encrypted data now at risk of exposure?

Thanks, everyone!

Answer 1

All a denial of service attack (of which a DDoS is a specific type) does is deny legitimate users access to the site. Anything further is a separate attack. Any repercussions are just those arising from the site no longer being accessible to legitimate users for a time (availability being one of the three pillars of security, which is why this is a security issue even though there is no data breach and no malicious users get control of the site).