The HTML 4.01 Frameset or the XHTML 1.0 Frameset Doctype must be used for framesets.
The main purpose of this tutorial was initially to show how IE6 and Firefox differ because IE6 will still be used for some time but now shows differences between other browsers as well.
IE7 is more like Firefox than IE6 but there are still some differences.
Opera, Safari and Google Chrome generally process code in a similar way to Firefox.
Some of the examples are provided just to show problems, others show solutions that work in Firefox, IE, Opera and Safari. There are always several ways to code and my examples may not suit your page if they conflict with other code in your page, so look at other tutorials in addition to mine.
Remember that tutorials can often be out of date as well as offering alternative solutions. It is recommended that you use the HTML 4.01 Strict Doctype where possible (or HTML5, see below).
The XHTML 1.0 doctype is often used but see the comments in the next section "HTML or XHTML".
The XHTML 1.1 DTD Doctype is not recommended where web pages are designed for the general public, some of whom will still be using old browsers which will not operate the XHTML 1.1 standards.
IE8 is much better than previous IE versions and substantially like Firefox.
Google Chrome is based on the same Web Kit engine as Safari.
IE9 & above updates are mainly related to HTML 5 and CSS3 issues and display to a large extent like other main browsers.
There are introductions to the more common uses of HTML and CSS coding as listed below.