Web Host

Web hosts are the companies that provide space on servers they own to individuals or organizations to make their own website accessible via World Wide Web.
Web host companies provide server space or server completely for rent or lease as well as internet connection.The most basic web hosting services is different generally.The most basic is Web page and a file hosting to upload files via file transfer protocol(FTP) or web interface. People can also obtain Web page hosting from other, alternative service providers. Personal web site hosting is typically free, advertisement-sponsored, or inexpensive. Business web site hosting often has a higher expense.
Personal websites require generally single page hosting. A complete site requires packages that provide database support and application development platforms( E.g. – PHP, Java, Ruby on Rails, ASP and .NET etc). These facilities allow users to write or install scripts for their application.
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. Some hosts specialize in certain software or services (e.g. e-commerce). They are commonly used by larger companies to outsource network infrastructure to a hosting company.

Reliability and uptime

The availability of a website is measured by the percentage of a year in which the website is publically accessible and reachable via the internet.
The formula to determine a system’s availability is relatively easy: Total time = 365 days per year * 24 hours per day * 60 minutes per hour = 525,600 minutes per year. To calculate how many minutes of downtime your system may experience per year, you can take your uptime guarantee and multiply it by total time in a year.
In this example I’ll use 99.99%: (1 – .9999) * 525,600 = allowable minutes down per year.

A hosting provider’s SLAs may include a certain amount of scheduled downtime per year so that they can 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 verbage 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.

Types of hosting

Free web hosting service: offered by many companies with limited services, sometimes have advertisements, and offer limited resources when compared to paid hosting.
Shared web hosting service: one’s website is placed on the same server as many other sites, ranging from a few to hundreds or thousands. Typically, all domains may share a common pool of server resources, such as RAM and the CPU.
Reseller web hosting: allows clients to become web hosts themselves. They may have their own virtual dedicated server to a main server. Many resellers provide a nearly identical service to their provider’s shared hosting plan and provide the technical support themselves.
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 users may have root access to their own virtual space.
Dedicated hosting service: the user gets his or her own Web server and gains full control over it ,however the user typically does not own the server but user has full administrative access to the server.