Learning HTML 3.2 by Examples, section 3 General remarks on the syntax of HTML:

Case sensitivity

As regards to tag and attribute names and most keyword-like attribute values, HTML is case insensitive. You can, for example, type TITLE or Title or title or even tItLE if you like. As an exception, the value of a TYPE attribute in an OL element is case sensitive.

In this document, upper case letters are used for the above-mentioned constructs. This may help the reader distinguish HTML code from normal text. The modern trend is to use lower case, and this is a requirement in XHTML.

Beware that the following constructs are (in general) case sensitive:

Date of last update: 2010-12-16.
This page belongs to the free information site IT and communication, section Web authoring and surfing, by Jukka "Yucca" Korpela.