Hypertext Markup Language (HTML) is an example of Standard Generalized Markup Language (SGML). Such files (SGML file) {HTML file} are text files.
tags
HTML uses tags to open and close formatting. Tags can be in any order or relation. Tags start with less-than signs and close with greater-than signs.
semantics
HTML has no semantics.
comment
<!-- comment --> inserts comment.
format
HTML files have a document-type line first, heading section second, and body section last.
document type line
<!DOCTYPE html> starts HTML 5 files.
beginning and ending lines
<HTML LANG="en-US"> is after the document-type line. </HTML> is at file end.
heading block
<HEAD> is after <HTML>, to start heading block.
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=UTF-8"> names content type for search engines.
<META HTTP-EQUIV="Expires" CONTENT="0"> expires page for search engines.
<TITLE>Title</TITLE> inserts title.
<META HTTP-EQUIV="keywords" CONTENT="keyword1, ..., keyword25"> or <META NAME="keywords" CONTENT="keyword1, ..., keyword25"> specifies up to 25 keywords for search engines.
<META NAME="description" CONTENT="25-word description"> describes HTML pages for search engines, using up to 25 words.
<META NAME="robots" CONTENT="noindex"> excludes indexing by search engines. <META NAME="robots" CONTENT="nofollow"> excludes searching for links by search engines. <META NAME="robots" CONTENT="noindex, nofollow"> excludes indexing by search engines and searching for links by search engines.
<STYLE TYPE="text/css"> starts the list of style attributes. HTML styles include: P, H1, H2, H3, H4, H5, H6, H7, A, and LI. P is paragraph. H1 through H7 are headings. A is anchor for name, id, and references. LI is list element. HTML styles, such as "color: blue" are in braces. text-align: center; font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12px; font-weight: bold; font-style: italic; color: red; text-decoration: none; are examples.
<LINK HREF="stylesheet.css" REL="stylesheet" TYPE="text/css"> points to a style sheet.
</STYLE> ends the list.
HTML can use CGI to add programs. <SCRIPT LANGUAGE="JavaScript" TYPE="text/javascript" SRC="path/file.js"></SCRIPT> specifies Java script to run program. <IMG ALT="Counter" SRC="/cgi-bin/counter.pl"> specifies Counter image. <A HREF="http://.../cgi-bin/guestbook.cgi">View My Guestbook</A> uses guestbook.
</HEAD> ends heading block.
body beginning and ending
After heading block, <BODY> starts body block. <BODY STYLE="background-image: url(path/file_name.gif); background-repeat: no-repeat;"> uses the STYLE attribute to specify parameters. At line before </HTML>, </BODY> ends BODY block.
paragraph, heading, and section
<P>...</P> is for paragraph, which has blank lines before and after.
<BR> is for line feed.
<H1>...</H1> is for heading 1. Headings 2 through 7 are similar.
<DIV>...</DIV> is for text section or page division, with blank lines before and after.
<SPAN>...</SPAN> is for paragraph phrase.
<OL> <LI>...</LI> </OL> is for list.
style tag and attribute
<P STYLE="text-align: center; font-family: Verdana, Arial, Helvetica, sans-serif; font-weight: bold; font-size: 12px; font-style: italic; color: red; text-decoration: none;"> specifies parameters.
For font-family, use fonts found on all browsers, such as Courier, Times, Arial, or Helvetica. font-family:sans-serif includes Verdana, Arial, and Helvetica. font-family:serif includes Times and Courier.
For font-size, use font-size:larger, font-size:smaller, or font-size:normal.
For font-weight, use font-weight:bold or font-weight:normal.
For font-style, use font-style:italic or font-style:normal.
For color, use hexadecimal string, such as color:FFFFFF for black and color:000000 for white, or use color name, such as color:blue, color:red, or color:green.
For text-decoration, use text-decoration:none to remove underlines from links.
table
<TABLE BORDER="0" WIDTH="640" CELLPADDING="0" CELLSPACING="0" > starts table, with border, width, and cell size. WIDTH="100%" uses percent. <TR>...</TR> is for table row. <TD COLSPAN="3" WIDTH="100%" ALIGN="left" VALIGN="middle">...</TD> is for table-row detail, such as column entry or line, with column span, width, horizontal alignment, and vertical alignment. </TABLE> ends table.
image
<IMG SRC="/x/x/xxx.gif" WIDTH="15" HEIGHT="10" HSPACE="0" VSPACE="0"> is for image, with source file, width, height, horizontal spacing, and vertical spacing.
jumping
<A HREF="#Glossary">Glossary</A> jumps to same-file position marked by <A NAME="Glossary"></A>. If there is no marked position, program searches for first occurrence in file.
anchor and linking
<A HREF="path/file_name">link_name</A> is for linking to a file or URI by clicking on the link name. <A HREF="path/file_name#ID">link_name</A> is for linking to a file or URI and jumping to the ID in the file. <A HREF="path/file_name.jpg" TARGET="_blank">image</A> opens a new window. <A HREF="http://x/x/xxx.pdf" NAME="x" ONMOUSEOVER="ft(this)"></A> shows something when cursor mouses over text.
URI Escape Characters
Use % for Unicode (and ISO-Latin) hexadecimal numbers. Always encode the following URI characters. space = %20. double quotation mark = %22. # = %23. % = %25. < = %3C. > = %3E. [ = %5B. backslash = %5C. ] = %5D. ^ = %5E. ` = %60 = opening single quote. { = %7B. | = %7C. } = %7D. ~ = %7E. Period, apostrophe, and hyphen are OK. Do not use parentheses, underscore, exclamation mark, or asterisk.
URI reserved characters define syntax. If used in URIs, encode them. $ = %24. & = %26. + = %2B. , = %2C. / = %2F. : = %3A. ; = %3B. = = %3D. ? = %3F. @ = %40.
characters
Unicode (and ISO-Latin) characters 0 to 31 and 127 are ASCII control characters and do not print. tab = 9. carriage return = 13.
HTML recognizes the following Unicode, ASCII, and ANSI characters: blank ! double quotation mark # $ % ' ( ) * + , - / 0 1 2 3 4 5 6 7 8 9 : ; = ? @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [ backslash ] ^ _ ` a b c d e f g h i j k l m n o p q r s t u v w x y z right brace left brace | ~ ¢ £ ± µ.
HTML Escape Characters
For other characters or for escaping characters, use &#NNN; for Unicode (and ISO-Latin) decimal numbers or &...; for alphabetic. 000 to 031 have no printing characters. 009 = tab. 013 = carriage return.
032 = sp = blank = space. 033 = excl = !. 034 = quot = double quotation mark. 035 = num = #. 036 = dollar = $. 037 = percnt = %. 038 = amp = & (ampersand). 039 = apos = ' = apostrophe = closing single quote. 040 = lpar = (. 041 = rpar = ). 042 = ast = *. 043 = plus = +. 044 = comma = ,. 045 = hyphen = dash = -. 046 = period = . 047 = sol = / (solidus). 048 to 057 are digits 0 to 9. 058 = colon = :. 059 = semi = ;. 060 = lt = <. 061 = equals = =. 062 = gt = >. 063 = quest = ?. 064 = commat = @.
065 to 090 are letters A to Z.
091 = lsqb = [. 092 = bsol = backslash. 093 = rsqb = ]. 094 = caret = ^. 095 = lowbar = _. 096 = ` (accent grave).
097 to 122 are letters a to z.
123 = lcub = left brace = left curly bracket. 124 = verbar = |. 125 = rcub = right brace = right curly bracket. 126 = tilde = sim = ~. 127 is for Delete.
ISO-Latin characters 128 to 255 are not in the ASCII set and may not print.
Unicode does not use ANSI 128 to 159.
Unicode and ANSI control characters
000 = NUL (Null character). 001 = SOH (Start of Header). 002 = STX (Start of Text). 003 = ETX (End of Text). 004 = EOT (End of Transmission). 005 = ENQ (Enquiry). 006 = ACK (Acknowledgment). 007 = BEL (Bell). 008 = BS (Backspace). 009 = HT (Horizontal Tab). 010 = LF (Line Feed). 011 = VT (Vertical Tab). 012 = FF (Form Feed). 013 = CR (Carriage Return). 014 = SO (Shift Out). 015 = SI (Shift In). 016 = DLE (Data Link Escape). 017 = DC1 (XON)(Device Control 1). 018 = DC2 (Device Control 2). 019 = DC3 (XOFF or Device Control 3). 020 = DC4 (Device Control 4). 021 = NAK (Negative Acknowledgement). 022 = SYN (Synchronous Idle). 023 = ETB (End of Transmission Block). 024 = CAN (Cancel). 025 = EM (End of Medium). 026 = SUB (Substitute). 027 = ESC (Escape). 028 = FS (File Separator). 029 = GS (Group Separator). 030 = RS (Request to Send or Record Separator). 031 = US (Unit Separator).
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Date Modified: 2022.0224