A web service always hides the internal complexity of the service to its clients. For an example, an airliner which is selling tickets via a third party portal is only gathering end user info via a web service and in return it is providing ticket. The portal which is selling ticket doesn't have to bother about the internal complexity of the airlines ticket reservation systems.
Image hosts also allow tools such as the ability to create photoblogs/galleries with your images, or add them to a slide show for easier viewing. Some offer more advanced tools such as the ability for anl to ato an image they uploaded, sideloaders, or browser sidebars. Other hosts have introduced novel features such as the ability to automatically resize images down to a user-selected size. A Flickr tool allows one to upload photos using a camera phone with email capability.
Privacy options are available if you don't want your photos to be viewed publicly, and you can easily share a single photo or an entire album with anyone you like. ImageShack also hosts photos for businesses and has several applications (both for mobile and the web) that you can take advantage of to make managing and sharing your photos even easier.
When you build a website, you want visitors to come and see what you've done. To get them there, you need a unique domain name that connects to your sites servers. Domain name registration is required to ensure that no one else in the world can claim ownership of your web site's address and to make finding your website simple. Find your one of a kind domain name.