Web Hosting in its simplest form is a space on a web server dedicated to a customers own files, normally a website or web page. The server runs for 24 hours, 7 days a week, 365 days of the year, just waiting for requests from a web browser. Think of web hosting as a folder that has a finite amount of disk space allocated to it and its owner can create files and folders within it but not outside of the main folder.
Domain Names are used to point a request to these web hosting folders so that the files/folders can be reached and viewed easily.
Many Web Hosting plans typically include email services too, so not only can you host a website, you can also set up email addresses using your chosen Domain Name so that other users can email you using your chosen Domain Name. When another user emails you, a copy of her email is sent to the server that’s hosting your website/email. The server then holds on to that email until such time that you log in and download your emails using an email client such as Mac Mail, Windows Mail, Outlook or Thunderbird. Once the email is downloaded, the copy of the email on the server is normally removed, but it is possible to set up email services to keep all email on the server for safe keeping. Also if you have multiple devices such as a PC and a mobile phone this is especially useful so that both devices get a copy of all emails. The three most common email services are POP, IMAP and MAPI and we may discuss these in more depth later.
The above is an example of shared web hosting, where the owner has a folder on a server that they can upload files/folders to. Other web sites may also exists in other folders next to your own and owned by other users. You will not be able to see these other folders and they will not see yours, but there may be many other websites running from the same server. Shared Web Hosting is one of the most cost effective Web Hosting solutions. Perhaps the best analogy here is shared hosting is similar to a shared office block, where multiple companies rent a room or rooms within the entire block. A company cannot access other offices but can access and do business from their own office.
You can also have an entire web server to yourself, especially if you have a large site, need a lot of space or even to host multiple sites yourself. Web servers come in two main flavours, Dedicated Servers and Virtual Servers. A Dedicated Server is a physical device in a datacentre (more on datacentres in a future post) that the owner has exclusive access to. The owner can reinstall the operating system, reboot the server at any time and generally do anything they wish (within the limitations of an agreement and the law) on this server. All of the servers Memory, its Processors and its Hard Disks are exclusively for the use of the owner and what they decide to run on the server.
A Virtual Server is almost exactly the same; you can reinstall the OS, reboot, install anything you wish while also having exclusive access to the allocated memory, Processors and Hard Disk space. The difference is that Virtual Servers normally sit on large physical servers carrying many Gigabytes of memory, many Terabytes of disk space and likely many Processors all on one machine to accommodate multiple Virtual Servers without issue. Its also common to have multiple Virtual Servers on one physical server so in that respect its similar to the shared hosting above but with a lot more flexibility as to how you can use the Virtual Machine.