Private server is a server machine that is privately owned by individual. As servers need adequate internet connection, power and are also noisy, they are often allocated in the colocation centre

Colocation centre

A colocation centre or colocation center , is a type of data centre where equipment space and bandwidth are available for rental to retail customers...

. Some centers also offer rack space for the single machine for $99 per month or about. The price is comparable to the price of the virtual private server (that is only a slice of the physical computer) and cheaper than the price of dedicated (rented) server with similar capabilities. Servers are available on the market same way as laptops or desktops are available and can be purchased by individual already pre-configured. Ordinary desktop computers are not suitable to house in the server centers as servers have specific form factor that allows to fit many them into standard rack. This group also includes custom-designed experimental servers, made by hobbyists

Before the rise of virtualization, the dedicated machine was necessary to implement any project that requires the server to run deeply custom stack of the software, impossible to configure without the root access. The first providers only allowed to upload static HTML, considering insecure to run user-provided code on a server side. Where execution of such code was allowed, strict constraints were usually placed on the usage of memory and CPU resources, frequently also putting some strict skeleton of the infrastructure (for instance, only scripts on the top of pre-installed LAMP

LAMP (software bundle)

LAMP is an acronym for a solution stack of free, open source software, referring to the first letters of Linux , Apache HTTP Server, MySQL and PHP , principal components to build a viable general purpose web server.The GNU project is advocating people to use the term "GLAMP" since what is known as...

 framework). Various restrictions exist up to now as only sole ownership and responsibility makes "misuse" pointless hence quotas and restrictions redundant. The only resource that still needs control is the network traffic.

While virtual server can also offer high degree of freedom and superuser

Superuser

On many computer operating systems, the superuser is a special user account used for system administration. Depending on the operating system, the actual name of this account might be: root, administrator or supervisor....

 access, it is limited in resources as the same physical server is shared by multiple projects.

Usage areas

• Private server can specifically mean a server emulator
  Server emulator
  Server emulator, a term that is widely used to describe reimplementation of MMORPG game servers, typically clones proprietary commercial software by a third party. The term "private server" is also used while it may not be accurate as often the legitimate server is also privately owned...
  
  , a reimplementation of MMORPG game server, typically a clone of proprietary commercial software by a third party. This meaning may be confusing as also the legitimate server that the emulator emulates is privately owned
  Private property
  Private property is the right of persons and firms to obtain, own, control, employ, dispose of, and bequeath land, capital, and other forms of property. Private property is distinguishable from public property, which refers to assets owned by a state, community or government rather than by...
  
  . Collocation center agreements typically disallow using a server to engage in illegal activities of any kind.
• If the game is available under open source license, it may be fully legal to run a server for it.
• Private machines are also used in various experimental projects such as non-functional MMORPG games under development or various innovative startups, if the owner believes that advantages of such a decision are important for a particular case.
• Successful projects with very high traffic may have adequate demand for resources to justify the use of a dedicated owned machine.

Advantages

• The machine can by fully locked for any access by anyone except owner.
• The owner has full freedom in choosing the server functions and software stack.
• The housing price tends to be cheaper than for the similar dedicated server as it does not include the price for renting the equipment.
• The server activities are only regulated by the law and not by policies of the hosting provider.
• The owned computer can offer much more disk space, memory, CPU time and other resources than shared, virtual private or even a typical dedicated server. As of 2011, some models support as much as 36 hard drives than can hold up to 72 Tb of data, enough to store significant part of the whole web. Similarly, servers may offer up till several hundred Gb of RAM - the two orders of magnitude more than it is possible to get with shared hosting plan. Some servers offer GPGPU
  GPGPU
  General-purpose computing on graphics processing units is the technique of using a GPU, which typically handles computation only for computer graphics, to perform computation in applications traditionally handled by the CPU...
  
  cards that can be used to serve generated images. However high end machine is more expensive to house as the housing price depends on size and may also depend on energy consumption.

Disadvantages

• The dedicated machine is an overkill for many web projects. Buying limited resources with web hosting plan may actually be cheaper.
• The owner must be able to manage software and ensure security (it is possible to purchase security audit).
• The price of the new server is comparable to the price of the used car - several thousand to several tens of thousand dollars, depending on configuration. This may be too expensive for the occasional hobby purchase but is an acceptable price for some business startup even without investing company behind.
• With very high end hardware, the traffic speed may become a bottleneck. Multiple servers, scattered thought the world, may be able to handle more connections even when each of them is less capable.