Tham khảo tài liệu 'tự học html và css trong 1 giờ - part 9', công nghệ thông tin, đồ họa - thiết kế - flash phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 56 I LESSON 3 Introducing HTML and XHTML be just about any editor more about this subject in Programs to Help You Write HTML section later can read them. HTML files contain the following The text of the page itself HTML tags that indicate page elements structure formatting and hypertext links to other pages or to included media Most HTML tags look something like the following thetagname affected text thetagname The tag name itself here thetagname is enclosed in brackets . HTML tags generally have a beginning and an ending tag surrounding the text they affect. The beginning tag turns on a feature such as headings bold and so on and the ending tag turns it off. Closing tags have the tag name preceded by a slash . The opening tag for example p for paragraphs and closing tag for example p for paragraphs compose what is officially called an HTML element. CAUTION__ Be aware of the difference between the forward slash mentioned with relation to tags and backslashes which are used by DOS and Windows in directory references on hard drives as in C window or other directory paths . If you accidentally use the backslash in place of a forward slash in HTML the browser won t recognize the ending tags. Not all HTML tags have both an opening and closing tag. Some tags are only one-sided and still other tags are containers that hold extra information and text inside the brackets. XHTML however requires that all tags be closed. You ll learn the proper way to open and close the tags as the book progresses. Another difference between HTML and XHTML relates to usage of lowercase tags and attributes. HTML tags are not case-sensitive that is you can specify them in uppercase lowercase or in any mixture. So HTML is the same as html which is the same as HtMl . This isn t the case for XHTML where all tag and attribute names must be written in lowercase. To get you thinking in this mindset the examples in this book display tag and attribute names in bold lowercase text. .
