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A web hosting service is a type of Internet hosting service that hosts websites for clients, i.e. it offers the facilities required for them to create and maintain a site and makes it accessible on the World Wide Web. Companies providing web hosting services are sometimes called web hosts.
Typically, web hosting requires the following:
- one or more servers to act as the host(s) for the sites; servers may be physical or virtual
- colocation for the server(s), providing physical space, electricity, and Internet connectivity;
- Domain Name System configuration to define name(s) for the sites and point them to the hosting server(s);
- a web server running on the host;
- for each site hosted on the server:
- space on the server(s) to hold the files making up the site
- site-specific configuration
- often, a database;
- software and credentials allowing the client to access these, enabling them to create, configure, and modify the site;
- email connectivity allowing the host and site to send email to the client
History
Until 1991, the Internet was restricted to use only
"... for research and education in the sciences and engineering
..."[1][2] and was used for email, telnet, FTP and USENET traffic—but only
a tiny number of web pages. The World Wide Web protocols had only just been
written[3] and not until the end of 1993 would there be a graphical web browser
for Mac or Windows computers.[4] Even after there was some opening up of
internet access, the situation was confused[clarification needed] until
1995.[5]
To host a website on the internet, an individual or company
would need their own computer or server.[6] As not all companies had the budget
or expertise to do this, web hosting services began to offer to host users'
websites on their own servers, without the client needing to own the necessary
infrastructure required to operate the website. The owners of the websites,
also called webmasters, would be able to create a website that would be hosted
on the web hosting service's server and published to the web by the web hosting
service.
As the number of users on the World Wide Web grew, the
pressure for companies, both large and small, to have an online presence grew.
By 1995, companies such as GeoCities, Angelfire and Tripod were offering free
hosting.[7]
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Classification
Smaller hosting services
The most basic is web page and small-scale file hosting,
where files can be uploaded via File Transfer Protocol (FTP) or a Web
interface. The files are usually delivered to the Web "as is" or with
minimal processing. Many Internet service providers (ISPs) offer this service
free to subscribers. Individuals and organizations may also obtain Web page
hosting from alternative service providers.
Free web hosting service is offered by different companies
with limited services, sometimes supported by advertisements, and often limited
when compared to paid hosting.
Single page hosting is generally sufficient for personal web
pages. Personal web site hosting is typically free, advertisement-sponsored, or
inexpensive. Business web site hosting often has a higher expense depending
upon the size and type of the site.
Larger hosting services
Many large companies that are not Internet service providers
need to be permanently connected to the web to send email, files, etc. to other
sites. The company may use the computer as a website host to provide details of
their goods and services and facilities for online orders.
A complex site calls for a more comprehensive package that
provides database support and application development platforms (e.g. ASP.NET,
ColdFusion, Java EE, Perl/Plack, PHP or Ruby on Rails). These facilities allow
customers to write or install scripts for applications like forums and content
management. Also, Secure Sockets Layer (SSL) is typically used for websites
that wish to keep the data transmitted more secure.
Types of hosting
A typical server "rack" commonly seen in
colocation centres
Internet hosting services can run Web servers. The scope of
web hosting services varies greatly.
Shared web hosting service
One's website is placed on the same server as many other
sites, ranging from a few sites to hundreds of websites. Typically, all domains
may share a common pool of server resources, such as RAM and the CPU. The
features available with this type of service can be quite basic and not
flexible in terms of software and updates. Resellers often sell shared web
hosting and web companies often have reseller accounts to provide hosting for
clients.
Reseller web hosting
Allows clients to become web hosts themselves. Resellers
could function, for individual domains, under any combination of these listed
types of hosting, depending on who they are affiliated with as a reseller.
Resellers' accounts may vary tremendously in size: they may have their own
virtual dedicated server to a colocated server. Many resellers provide a nearly
identical service to their provider's shared hosting plan and provide the
technical support themselves.
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Virtual Dedicated Server
Also known as a Virtual Private Server (VPS), divides server
resources into virtual servers, where resources can be allocated in a way that
does not directly reflect the underlying hardware. VPS will often be allocated
resources based on a one server to many VPSs relationship, however
virtualisation may be done for a number of reasons, including the ability to
move a VPS container between servers. The users may have root access to their
own virtual space. Customers are sometimes responsible for patching and
maintaining the server (unmanaged server) or the VPS provider may provide
server admin tasks for the customer (managed server).
Dedicated hosting service
The user gets his or her own Web server and gains full
control over it (user has root access for Linux/administrator access for
Windows); however, the user typically does not own the server. One type of
dedicated hosting is self-managed or unmanaged. This is usually the least
expensive for dedicated plans. The user has full administrative access to the
server, which means the client is responsible for the security and maintenance
of his own dedicated server.
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Managed hosting service
The user gets his or her own Web server but is not allowed
full control over it (user is denied root access for Linux/administrator access
for Windows); however, they are allowed to manage their data via FTP or other
remote management tools. The user is disallowed full control so that the
provider can guarantee quality of service by not allowing the user to modify
the server or potentially create configuration problems. The user typically
does not own the server. The server is leased to the client.
Colocation web hosting service
Similar to the dedicated web hosting service, but the user
owns the colo server; the hosting company provides physical space that the
server takes up and takes care of the server. This is the most powerful and
expensive type of web hosting service. In most cases, the colocation provider
may provide little to no support directly for their client's machine, providing
only the electrical, Internet access, and storage facilities for the server. In
most cases for colo, the client would have his or her own administrator visit
the data center on site to do any hardware upgrades or changes. Formerly, many
colocation providers would accept any system configuration for hosting, even
ones housed in desktop-style minitower cases, but most hosts now require rack
mount enclosures and standard system configurations.
Cloud hosting
This is a new type of hosting platform that allows customers
powerful, scalable and reliable hosting based on clustered load-balanced servers
and utility billing. A cloud hosted website may be more reliable than
alternatives since other computers in the cloud can compensate when a single
piece of hardware goes down. Also, local power disruptions or even natural
disasters are less problematic for cloud hosted sites, as cloud hosting is
decentralized. Cloud hosting also allows providers to charge users only for
resources consumed by the user, rather than a flat fee for the amount the user
expects they will use, or a fixed cost upfront hardware investment.
Alternatively, the lack of centralization may give users less control on where
their data is located which could be a problem for users with data security or
privacy concerns as per GDPR guidelines. Cloud hosting users can request
additional resources on-demand such as only during periods of peak traffic,
while offloading IT management to the cloud hosting service.
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Clustered hosting
Having multiple servers hosting the same content for better
resource utilization. Clustered servers are a perfect solution for
high-availability dedicated hosting, or creating a scalable web hosting
solution. A cluster may separate web serving from database hosting capability.
(Usually web hosts use clustered hosting for their shared hosting plans, as
there are multiple benefits to the mass managing of clients).[8]
Grid hosting
This form of distributed hosting is when a server cluster
acts like a grid and is composed of multiple nodes.
Home server
Usually a single machine placed in a private residence can
be used to host one or more web sites from a usually consumer-grade broadband
connection. These can be purpose-built machines or more commonly old PCs. Some
ISPs actively attempt to block home servers by disallowing incoming requests to
TCP port 80 of the user's connection and by refusing to provide static IP
addresses. A common way to attain a reliable DNS host name is by creating an
account with a dynamic DNS service. A dynamic DNS service will automatically
change the IP address that a URL points to when the IP address changes.[9]
Some specific types of hosting provided by web host service
providers:
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• File
hosting service: hosts files, not web pages
• Image
hosting service
• Video
hosting service
• Blog
hosting service
• Paste bin
• Shopping
cart software
• E-mail
hosting service
Host management
Multiple racks of servers
The host may also provide an interface or control panel for
managing the Web server and installing scripts, as well as other modules and
service applications like e-mail. A web server that does not use a control
panel for managing the hosting account, is often referred to as a
"headless" server. Some hosts specialize in certain software or
services (e.g. e-commerce, blogs, etc.).
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Reliability and uptime
The availability of a website is measured by the percentage
of a year in which the website is publicly accessible and reachable via the
Internet. This is different from measuring the uptime of a system. Uptime
refers to the system itself being online. Uptime does not take into account
being able to reach it as in the event of a network outage.[citation needed] A
hosting provider's Service Level Agreement (SLA) may include a certain amount
of scheduled downtime per year in order to perform maintenance on the systems.
This scheduled downtime is often excluded from the SLA timeframe, and needs to
be subtracted from the Total Time when availability is calculated. Depending on
the wording of an SLA, if the availability of a system drops below that in the
signed SLA, a hosting provider often will provide a partial refund for time
lost. How downtime is determined changes from provider to provider, therefore
reading the SLA is imperative.[10] Not all providers release uptime
statistics.[11] Most hosting providers will guarantee at least 99.9% uptime
which will allow for 43m of downtime per month, or 8h 45m of downtime per year.
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