#pair=en|es&hl=es&ie=UTF-8&ie=UTF-8&oe=UTF-8&prev=/language_tools"> What is Bandwidth / Download?

Bandwidth is a measure of the amount of data passing through a network at a given time. Things like huge images on web pages and needless questions posted to Usenet newsgroups waste bandwidth which could be better utilized for transferring information.

In computer networks, bandwidth is often used as a synonym for data transfer rate - the amount of data that can be carried from one point to another in a given time period (usually a second). This kind of bandwidth is usually expressed in bits (of data) per second (bps). Occasionally, it's expressed as bytes per second (Bps). A modem that works at 57,600 bps has twice the bandwidth of a modem that works at 28,800 bps. In general, a link with a high bandwidth is one that may be able to carry enough information to sustain the succession of images in a video presentation.

It should be remembered that a real communications path usually consists of a succession of links, each with its own bandwidth. If one of these is much slower than the rest, it is said to be a bandwidth bottleneck.

Wasted Bandwidth

A full page of English text is about 16,000 bits. A fast modem can move about 15,000 bits in one second. Full-motion full-screen video would require roughly 10,000,000 bits-per-second, depending on compression. Some points have narrow bandwidth (indicating not much information can flow through at one time), and others have high bandwidth (indicating a great deal of information can flow through at one time). This term is commonly used in reference to "wasted bandwidth," indicating that some (or most) of the information flowing by a point is of no use to a user. "Wasted bandwidth" might include overloading a site's network connection (thus curtailing other users' use of the lines) or including lengthy signature files in Usenet postings or discussion groups. "Wasted bandwidth" is often relative: What one person views as wasteful might be essential to someone else.

How much bandwidth do I need?

When choosing a host, the amount of bandwidth you choose to purchase can be crucial to the success of your site. Generally speaking, the more amount of bandwidth you have, the more traffic your site will be able to handle at one time.

To determine how much bandwidth you will need, you must estimate how big each page on your site is and how many people are going to view it. To do this, add up the size of every image on the page and the size of the page's HTML files, and multiply that by the amount of views for that page you expect per month. For example, if you had three 10k images on your page and a 2k HTML file, you would have 32k of data on that page. Multiply that by your expected page views (let's say in this case it is 100,000 per month), and you get 3.2 G of data to be transferred that month for that page. Now calculate this for each page, and you will know approximately how much bandwidth your entire site requires.

How can I save bandwidth?

There are a number of ways to optimize your bandwidth usage. First and foremost, keep your pages small as possible. This means tight HTML programming to reduce file size, and compacting your pictures and graphics to reduce image size (NetMechanic has a free, easy-to- use file compression utility). Use the JPEG image format for your photos and the GIF format for graphics, as their compression abilities are second to none.

Take a look at Dr. HTML's site for some useful tools that will analyze your site's image sizes, transfer amounts, table structure and more.

Another way to save bandwidth is to use photos and images on your site that are actually stored elsewhere. You can do this by replacing the file name in your IMG SRC tag with a URL. Before doing this, however, make sure you have the permission of the site you are linking to. Otherwise, you are "stealing bandwidth", which is considered pirating and is therefore illegal (for more information, see "preventing bandwidth theft" below).

Cascading Style Sheets (CSS) is also an effective way to save bandwidth. It is designed to reduce HTML file size by attributing values for any HTML element/command at the beginning of the document.

Preventing bandwidth theft

Using another site's images by linking to them in your IMG SRC tag without permission means is a form of double piracy; that is, you are pirating both the site's image and bandwidth. As unethical as it may be, it is a reality many webmasters have to deal with on a daily basis.

The most basic method of preventing bandwidth theft is policing. This entails analyzing search engines, logs and other sites to find out who is using your images (and therefore your bandwidth) without permission. Once you have located the offending party/parties, you can contact them and order them to stop linking to your site (if they try to feed you a story about everything on the Internet being in the "public domain", don't buy it). Unfortunately, policing sites yourself is a time-consuming task.

Related resources

How to Reduce Web Hosting Bandwidth Usage
Using too much bandwidth on your hosting plan will result in paying higher fees. Learn how to cut your bandwidth usage and save money.

Bandwidth Or Data Transfer
Too often web hosts talk about bandwidth and data transfer in the same breath but truth be known 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.

Bandwidth Or Data Transfer - Which is Which?
Too often web hosts talk about bandwidth and data transfer in the same breath but truth be known 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.


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