First, understand that it’s very hard to build a Web page that displays perfectly on every version of every browser running on every computer. And doing so may require you to leave out features that you want to have on your Web page.

Your Web browser is a translation device. It takes a document written in the HTML language and translates it into a formatted Web page. The result of this translation is a little like giving two human translators a sentence written in Greek and asking them to translate it into English. Both will get the meaning across, but may not use the same words to do so.

The basic rules for translating HTML documents are established by the World Wide Web consortium, which publishes the official HTML standards.

Different browsers interpretation of HTML, computer types, and font sizes settings, as well as browser bugs (and other settings, screen sizes and resolution settings also vary computer to computer) are not controllable by the website designer.

Different Browsers

Not only are there different browsers, but also different versions of each browser, (IE6, IE7, FF1, FF2, FF3, etc).

IE and FF (and Safari) each has different rendering “engines”.
IE uses Trident(MSHTML) as its rendering engine on Windows. IE for Mac used a different rendering engine than MSHTML.
Firefox uses Gecko. Safari… WebCore (KHTML and KWQ as the adapter library).
These different rendering engines do not always display the website (code) the same.

Different Computer Types

In theory, if you view your page on both a PC and a Mac using the same version of the same browser, it should display the same, right?

In practice that’s rarely the case. There are three reasons for this:

* Font Availability. When you tell your Web page to use a particular typeface, such as “Arial,” you may not always get the font you want. Fonts are a computer resource, and not all computers have the same fonts as your computer. That’s true even between different PCs, but it’s especially true between the PC and the Mac. If the typeface of your page suddenly changes between these computers, the website probably used a font that isn’t available on both computer types.

* Font Size. The Mac will generally render your typeface in a smaller pixel size than the PC will. That’s especially true if you use the FONT tag to set your type size, since this tag uses abstract units to define size.

* Internet Explorer. Microsoft outsources the development of Internet Explorer for the Mac, and so to a large extent this is a different browser from the PC version. In particular, the Mac version of Internet Explorer is prone to quirks and bugs that you won’t see in the PC version.

Different Font Sizes

Most browsers allow users to customize their default font size. Many users who work on computers all day do this to reduce eye strain. As a result, user preferences may cause the typeface that was used to design your Web page to increase as much as 50% larger in a user’s browser.
Each computer can have different settings for each browser (IE, FF) causing display differences between browsers on same computer system.

Browser Bugs

Building a Web page that displays well on all browsers isn’t easy. To make matters worse, sometimes you’ve done everything right, and your page still doesn’t display correctly under one specific browser. It’s not your fault – you’ve just encountered a browser bug.
Unfortunately, browser bugs are a fact of life. Each browser has its own unique set of errors and quirks.

What To Do To Reduce Display Issues

The first step to solving browser compatibility problems is to determine which browsers really matter to you and then letting your WebMaster know BEFORE they create your website.

If building your own website, be sure to use valid code. Invalid HTML code can cause display problems that turn away visitors and hurt search engine promotion efforts. Coding errors may hide large amounts of your page content from search engines – even though human visitors see the content with no problem. That is, if they can find it.

We wish it were easy to cure browser display problems, but fixing them takes time and can be expensive if decided upon after the website is complete. And doing so may require you to leave out features that you want to have on your Web page.