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HTML
Consider this
example of HTML:--
<B>This is an
example of <I>overlapping</B>
HTML tags.</I>
The word overlapping is contained within both the <B>
and <I>
tags. A browser might be confused by this coding and might not display it
the way you intend. The only way to know is to check each popular browser
(which is time-consuming and impractical).
In general, avoid overlapping tags. Look at your tags and try pairing them
up. Tags (with the obvious exceptions of elements whose end tags may be
omitted, such as paragraphs) should be paired without an intervening tag
in between. Look again at the example above. You cannot pair the bold tags
without another tag in the middle (the first definition tag). Try matching
your coding up like this to see if you have any problem areas that should
be fixed before you release your files to a server.
HTML protocol allows
you to embed links within other HTML tags:--
<H1><A HREF="Destination.html">My
heading</A></H1>
Do not embed HTML
tags within an anchor:--
<A HREF="Destination.html">
<H1>My heading</H1>
</A>
Although most browsers currently handle this second example, the official
HTML specifications do not support this construct and your file will
probably not work with future browsers. Remember that browsers can be
forgiving when displaying improperly coded files. But that forgiveness may
not last to the next version of the software! When in doubt, code your
files according to the HTML specifications (see For More Information
below).
Character tags
modify the appearance of the text within other elements:--
<UL>
<LI><B>A bold list item</B>
<LI><I>An italic list item</I>
</UL>
Avoid embedding other types of HTML element tags. For example, you might
be tempted to embed a heading within a list in order to make the font size
larger:
<UL>
<LI><H1>A large heading</H1>
<LI><H2>Something slightly smaller</H2>
</UL>
Although some browsers handle this quite nicely, formatting of such coding
is unpredictable (because it is undefined). For compatibility with all
browsers, avoid these kinds of constructs. (The Netscape <FONT> tag,
which lets you specify how large individual characters will be displayed
in your window, is not currently part of the official HTML
specifications.)
What's the difference between embedding a <B> within a <LI>
tag as opposed to embedding a <H1> within a <LI>? Within HTML
the semantic meaning of <H1> is that it's the main heading of a
document and that it should be followed by the content of the document.
Therefore it doesn't make sense to find a <H1> within a list.
Character formatting tags also are generally not additive. For example,
you might expect that:
<B><I>some
text</I></B>
would produce bold-italic text. On some browsers it does; other browsers
interpret only the innermost tag.
Validate Your Code:-
When you put a document on a Web server, be sure to check the formatting
and each link (including named anchors). Ideally you will have someone
else read through and comment on your file(s) before you consider a
document finished.
You can run your coded files through one of several on-line HTML
validation services that will tell you if your code conforms to accepted
HTML. If you are not sure your coding conforms to HTML specifications,
this can be a useful teaching tool. Fortunately the service lets you
select the level of conformance you want for your files (i.e., strict,
level 2, level 3). If you want to use some codes that are not officially
part of the HTML specifications, this latitude is helpful.
Dummy Images:--
When an <IMG SRC> tag points to an image that does not exist, a
dummy image is substituted by your browser software. When this happens
during your final review of your files, make sure that the referenced
image does in fact exist, that the hyperlink has the correct information
in the URL, and that the file permission is set appropriately
(world-readable). Then check online again!
Update Your Files:--
If the contents of a file are static (such as a biography of George
Washington), no updating is probably needed. But for documents that are
time sensitive or covering a field that changes frequently, remember to
update your documents!
Updating is particularly important when the file contains information such
as a weekly schedule or a deadline for a program funding announcement.
Remove out-of-date files or note why something that appears dated is still
on a server (e.g., the program requirements will remain the same for the
next cycle so the file is still available as an interim reference).
Browsers Differ:--
Web browsers display HTML elements differently. Remember that not all
codes used in HTML files are interpreted by all browsers. Any code a
browser does not understand is usually ignored though.
You could spend a lot of time making your file "look perfect"
using your current browser. If you check that file using another browser,
it will likely display (a little or a lot) differently. Hence these words
of advice: code your files using correct HTML. Leave the interpreting to
the browsers and hope for the best.
You might want to include comments in your HTML files. Comments in HTML
are like comments in a computer program--the text you enter is not used by
the browser in any formatting and is not directly viewable by the reader
just as computer program comments are not used and are not viewable. The
comments are accessible if a reader views the source file, however.
Comments such as the name of the person updating a file, the software and
version used in creating a file, or the date that a minor edit was made
are the norm.
To include a comment, enter:
<!-- your comments
here -->
You must include the exclamation mark and the hyphens as shown.
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