The "Cloud" is often a misunderstood thing. When referring to it and websites, it's simply a way of storing your website online where many computers all balance the work load.
By sharing the resources available from many computers in tandem, this not only means that your website will load quicker, but it's also more protected against hardware failure; if one of the machines goes down, there are others to keep you up there.
Hosting in a Cloud environment as Net Grow does, coupled with using a Content Delivery Network such as Amazon or CloudFlare really sees a drastic increase in perceived web site performance. A CDN helps by caching, then serving, website content at very fast locations all around the world. It has a chance to determine a user's location and then pick the best & closest servers to them; so you know that whether someone is looking at your website in Australia to USA or Asia to Europe, they will always get the best experience.