Bandwidth

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This article is republished,being permitted by http://www.webhostingtalk.com
Hi! Everone
I republished last time definition of "Disc Space". When you visit web Hosting Hosting company's site,first line says Disc Space and second line says Bandwidth. So I decided to find an article for bandwidth which never learnt before and I was curious about the meaning.
The article below is good,but it is not easy to understand.  I do not understand bottom half so I have to read this art in the future again.
 Don's be discouraged to read this article if you are like me!?  I hope I can post easy one next time. Stay tuned!.
Click Most Updated Discount Coupon Codes & My Personal Web Hosting Recommendations if you are interested in those.
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 This article is republished,being permitted by http://www.webhostingtalk.com
In normal electronic terms, bandwidth refers to a range within a band of frequencies, or data sum being transmitted in a fixed amount of time. However, in the web hosting industry, bandwidth refers to the amount of data that is transferred between a server to its client computers within a certain period of usage.
Contents
1 Bandwidth or data transfer
2 How it affects your site
3 Determining your requirements
4 Unlimited plans
5 Reducing transfers
6 FTP bandwidth

Bandwidth or data transfer

Too often, web hosts talk about bandwidth and data transfer in the same breath, but they are different, although very closely related. Bandwidth is how much data can be transferred at a time, and data transfer is how much data is being transferred.

Think of it this way. If bandwidth were a bridge, then the bigger the bridge is, the more vehicles can pass through it. In comparison, data transfer is the number of vehicles allowed on the bridge in, say, a month. In essence, data transfer is the consumption of bandwidth.

How it affects your site

The less bandwidth you have, the slower your site loads, regardless of the visitor's connection type. If you have more visitors, some of them will have to wait their turn. The less data transfer you have, the more often you'll find your site unavailable because you've reached the maximum allowed until a new month rolls by or you upgrade your account.

Determining your requirements

Usually when a host talks about bandwidth, they are referring to your monthly transfer limit. So you need to figure out what is sufficient for your site to function. You'll need to gather some information; this is fairly easy to do if you already have a site. Most of this information is available from your traffic history. If you don't have an existing site, provide an optimistic estimate if you intend to heavily promote the site. Then get ready for some math.

Find out the daily averages of:

Number of visitors / expected number of visitors
Page size including the graphics of the page
Page views / expected pages viewed by each visitor

Then, multiply them as follows:

Visitors x Page size x Page views x 30 days = Monthly Website Transfer

You should also throw in a small margin or error to take into account email traffic and your own uploads to the server. If you offer downloads, then you should add the following:

Average/Expected downloads x File Size x 30 days = Monthly Download Transfer

Unlimited plans

Bandwidth is very expensive. All hosts are limited by their own allocations. Think back to the bridge. What happens is that each visitor to your site will be given a smaller lane to transfer the data, creating many tiny lanes therefore "unlimited". The more visitors you have, the smaller each lane will be, which makes each visitor wait for the page to load.

More often than not, there is little choice over your bandwidth, as your host controls this. Some hosts may limit the number of simultaneous connections, in affect slowing down your site and refusing some visitors. This is called throttling. If you're concerned about this, you should ask the host how they control bandwidth usage or purchase a package with more data transfer.

Reducing transfers

On the other hand, you can reduce your transfer amount by building simpler, more efficient websites and optimizing your graphics. Refrain from fancy Flash presentations or streaming audio. Use CSS, and call JavaScript externally instead of embedding it in every page. Remove unwanted tags, white space, and comments. Limit your META tags to those absolutely necessary. Having too many keywords is not search engine friendly. Besides, many search engines will only review the first few and ignore the rest.

Another good idea is to cache your website, but you might want to set an expiry date in the HTTP headers so that the browser will refresh the content after a certain time. Use mod-gzip. It could save you as much as 40% of your bandwidth. Out-of-control robots can also suck down your bandwidth like a black hole. So use robots.txt to keep spiders in check.

Also be aware of hotlinking, which is what happens when another website you don't control links to your images and other media. The other site is effectively stealing your bandwidth. You can prevent other sites from doing this by checking the HTTP referrer header to prevent hotlinking - this can save you a lot of bandwidth.

FTP bandwidth

It’s also important to realize that many hosting companies calculate amount of files or data transmitted to and from clients via FTP applications or file management system as part of bandwidth. This may not consume much bandwidth. However, for those that engage in frequent data, content, or image changes, they’ll end up increasing bandwidth consumption on a large scale.

Also, it should be noted that files and digital data such as music, movies, and software downloads must be considered before uploading them. Many visitors play and listen to or watch music and video files on websites or download them onto their hard disks; both activities could increase bandwidth consumption at alarming rate. The only precaution is to limit their uses on the website.