There are various ways in which a website can be compromised, a common threat is a DDoS (Distributed Denial of Service) attack. A DDoS attack occurs when a server is overloaded by a malicious user, this has the effect of blocking valid users from accessing the server rendering it useless. DDoS attacks are mostly carried out to blackmail the target website, Its of great inconvenience when a website comes under this sort of attack as it can render a site unreachable for the whole duration of the attack. A server has a finite amount of resources and connections that it can handle at any one time. A DDoS takes advantage of many computers at once to tie up all of the servers resources, each 'visitor' during the attack also comes from a different IP address. Overall this is an extremely disruptive practice that I would strongly discourage.
To explain a DDoS attack in another context - say that you own a store and I happen to send all of the people I know into your store all at once. All of the people I have sent in have no intention of buying anything or are even looking around, in essence all they are doing is taking up space and causing a nuisance. At the same time, because of the influx of 'fake' shoppers your true customers cant get into your store to buy anything.
Fortunately we have 1000GB per second DDoS protection with all of our packages here at Peters Web, we also have an extra layer of protection due to our association with Cloudflare (we use Cloudflare software when running Peters Web). We would highly recommend the use of Cloudflare (see Knowledgebase article here).
I have just scratched the surface here when mentioning DDoS attacks, as always please feel free to contact us by opening up a support ticket (open a ticket) with our hosting department, we will try to get back to you as soon as possible!