The terms “Shared Cloud” and “Shared Cloud Hosting” are not very different from Cloud Hosting. They also refer to an Internet Hosting service delivered from a group of servers. The term Shared Cloud Hosting (Shared Vloud) is not  precisely defined yet. However, a “Shared Cloud Hosting” could be considered a service delivered from a computer system in which the computing resources (processing resources) are distributed. To be considered as “Shared” any Cloud hosting service must be powered by a software platform which does not create isolated virtual instances. In a Shared Cloud, all data resides in a shared storage system or network (shared pool). Cloud accounts (name based or IP based virtual hosting) share the computing resources of all servers part of the system.

The term LAMP platform stands for: Linux, Apache, MySQL, and PHP/Perl/Python. Linux OS distributions are the core of the L.A.M.P. server software combination. It is the most popular among the web developers because of its stability and flexibility.

Apache is a open source HTTP Server management software and is probably the most popular web server automation program. It is developed and maintained by a large community of developers with the help of the Apache Software Foundation. The Apache is available for Unix, GNU, FreeBSD, Linux, Solaris, Novell, Mac OS X, Microsoft Windows  and other operating systems.

MySQL is a relational database management system (RDBMS), which when run on a server, provides multi-user access to a number of databases. There are more than 10 million servers that run MySQL.

PHP is a programming language designed for producing dynamic web pages and is used mainly in server-side application software. Perl and Python are also programing languages.

The term (phase) “Linux Hosting” refers to a web hosting service provided form a Linux OS (Unix) based web server. Various Liunux distributions are used as server operating systems. Most of the well known, reliable Internet hosting providers run Linux distributions on their web servers.

Linux OS and Linux based servers are very popular because of the open source software collaboration, which allows the source code to be used, modified and redistributed from anyone. The distribution could be commercial or non-commercial under the GNU General Public License. The Linux OS is packaged in a format known as a Linux distribution. Some of the most popular Linux distributions used on web servers are Red Hat Enterprice Linux, CentOS, Debian, (Ubuntu), Fedora and openSUSE.

Often the term Linux Hosting refers to L.A.M.P Hosting service.

Cloud Hosting is a Internet hosting service delivered from a Cloud computing generation IT infrastructure. Cloud computing term generally refers to a systems which combine the computing resources of a number of machines in order to provide High Availability, ability to scale up and down the services and more flexibility to the users.

The term Cloud Hosting can be also associated with another one – Clustered hosting. Despite that as of May 2011 the term Cloud Hosting is pretty broad term which is not precisely defined yet, we can consider any hosting service as a “Cloud” if it is delivered from a fully-redundant, multi-server system, in which the resources are dynamically scalable and often virtualized.

“VPS” is an abbreviation of Virtual Private Servers. This is a type of web hosting service achieved though dividing a physical server into a number of virtual instances. This is possible thought different virtualization techniques.

Virtual Private Server (VPS or VPS Hosting) is a broadly used term which refers to a virtual machine (VM). The virtual machines or VPS are functionally equivalent to a any physical server (dedicated server). Another term – Virtual Dedicated Server (VDS) – also refers to a virtual instance, however it is usually used to explain a virtual server result of different concept of virtualization – Full virtualization.

Any physical dedicated server runs a hypervisor which creates, destroys, and manages the resources of “guest” operating systems or virtual machines. The guest OS are allocated a percentage of resources of the physical machine. The Guest system or VPS may be fully virtualized, paravirtualized, or a hybrid of these two.

In a fully virtualized server, the guest represents an emulated or virtualized set of hardware. It is unaware that this hardware is not strictly physical. The hypervisor translates, maps, and converts requests from the VPS into the appropriate resource requests on the host, resulting in significant overhead.

In a paravirtualized (Paravirtualization) server, the VPS is aware of the hypervisor and interfaces directly with the underlying physical server’s resources. In this virtualization technique the hypervisor implements real-time access control and resource allocation. This results in near-native performance since the VPS sees the same hardware as the physical machine and can thus communicate with it natively. Linux OS supports this method of virtualization.

Advantages of Virtual Private Servers

• Owners and server administrators have full root access to the virtual machine
• Any VPS account is isolated from others accounts on the same physical server
• The VPS owner does not need to deal with hardware or to deal with any replacements or physical upgrades, because the web hosting provider is responsible for the management of the underlying physical server
• From user’s perspective the VPS are easy to be scaled up and down and used on a per demand basis
• A VPS is cheaper than a physical server with similar amount of resources

Disadvantages of Virtual Private Servers

• Compared to any form of Virtual Hosting (Shared Hosting) the VPS are hard to manage, because they require someone to do a system administration and maintenance, OS and applications’ installation, etc.
• Unlike physical dedicated servers, the CPU, RAM, HDD space, disk I/O and other computing resources are still shared between different users of the same underlying physical server. However in some forms of virtualization like Full virtualization, we can not say that the resources are shared.