PAGE LOADING TIME
PATIENCE IS HIGHLY OVERRATED

WHAT'S GOING ON?
When you are surfing the web, you are actually downloading web pages and images from a web-hosting server. A web-hosting server is a computer whose main function is to, "serve" web pages to anyone who is requesting them. You are requesting them when you type in the URL. The speed at which your web pages load is therefore determined by the "size of the files" you download, "the speed at which the server serves them", and the "rate at which they are traveling over the Internet."

ANATOMY OF A WEB PAGE
The first part of our loading time puzzle is the "size of the files". Almost all web pages are made up of several files: One HTML file which is the text and all the formatting language, and then all the image files for that page. A page may have no images, or it may have 30 images. Lets look at an example.

To download this web page you actually have to download 3 separate files, which your browser then assembles on your desktop. Total size of this download would be 43k. Our job as web designers is to keep the file sizes of our pages small enough to download quickly. We do this using the latest software and image compression technology.

THE SERVER
The second part of our loading time puzzle is "the speed at which the server serves the pages". If 500 web surfers all ask for the same page at the same time, the server can get bogged down, and loading speed will slow down. The home page at Yahoo gets 4 million hits a day. My personal web page gets 4 hits per month. Web hosting companies will tune their servers to apply more computing power to the sites that get the most hits. This is a new science and there is no way to predict exactly how many people will visit a site at once. Therefore we will always have to deal with an occasional slow server.

BANDWIDTH - THE PIPELINE ANALOGY
The third part of our loading time puzzle is "the rate at which they are traveling over the Internet". This is a complex subject. We will give a basic explanation of the concept of bandwidth and the factors that control it.

Bandwidth – The amount of data that can be transmitted in a fixed amount of time. Bandwidth is measured in bits per second, or bps. Experts often use the analogy of water in pipes to describe the way data flows over the Internet. Picture the Internet as a network of pipes which all have different widths. Larger pipes carry more water than the smaller ones. The heart of the Internet is made up of giant pipes called backbones, which span the globe. So how does your typical home user tap into these backbones?

BANDWIDTH - THE BIG PICTURE
Most businesses and home users get Internet access from an ISP (Internet Service Provider). The ISP leases a medium-sized pipe like an OC-192 or a T-1. For this example we will say they lease a T-1 line from the Telecommunications Company and then sell a limited number of individual accounts to customers who then share that T-1 line. The home user usually gets access by dialing in through a 56k phone line. They plug their phone line into a modem and the chain is complete.

DRIP … DRIP … … … DRIP
It is up to ISPs to set up accounts responsibly and avoid over-burdening their lines.
A T-1 carries 1,544Kbps
A phone line carries 56Kbps
1,544 divided by 56 = 27.
This means that 27 dial–up users can simultaneously share a T-1 line and all get full 56Kbps of bandwidth. In reality, we don’t all get on the Internet at the same time and so ISPs will sell more accounts than can fit on a T-1 line at once. Most of the time this is not a problem. But at peek Internet usage times – drip … drip … … … drip.
This example has been oversimplified to make a point: WE DON’T ALWAYS GET THE AMOUNT OF BANDWIDTH WE ARE SUPPOSED TO BE GETTING! Your rate of bandwidth actually fluctuates while you are surfing.

SUMMARY
3 things determine the speed at which web pages load:

• Size of the files you download
• Speed at which the server serves them
• Rate at which they are traveling over the Internet

Users have varying levels of access to the Internet. Some people may have a dedicated T-1 at work, and a 28Kbps modem at home. Some people still use 14Kbps modems! Even though their phone line can carry 56Kbps of data, they are only getting 14Kbps. Access is only as strong as the weakest link in the chain. (OR it only flows as fast as the tightest kink in the hose will let it). Today. DSL, Cable, and satellite Internet access are improving download speeds, but these technologies are all still much slower than a typical computer-to-computer Ethernet connection. Our job is to keep the file sizes down so that no matter who is viewing your site, they benefit from the fastest possible download performance.