Common HTML Errors
As stated in HTML How Do They Do That, browsers do not give error messages for improper HTML usage. A browser will just eat anything it doesn't understand. This can be frustrating when you put tags into a document and for some reason they don't appear. What follows is some common errors that one could make, the effect and / or what one can do to fix it.

Symptom: Disappearing Text (or Is Your Text Power Cord Connected?)

Don't make the background color and the text color the same!
Seriously, watch your colors. There are four color settings on the <BODY> tag you need concern yourself with. These colors should be visually distinct and be verified when they are on the server. Some HTML editors fool the browser when testing locally on the PC.
Accidently deleting a < or a >
You wish to type XX<i>hello</i> world XX, but the evil index finger reaches back and hits the backspace or delete key thereby generating <ihello</i> . What happens? See for yourself. XX world XX is what my browser (Netscape 3.01) did. The hello disappeared.

Stray < or > could also be a sign that you deleted the complementing angle bracket.

Make sure your browser supports color and font changes.

Symptom: Colors Are Not Working (or Is Your Color Power Cord Connected?)

Changes made to the <BODY> color didn't work.
This is easy. What happened is something was placed prior to the <BODY> tag or you accidently generated a second <BODY> tag. In HTML 3.2, the beginning of the document should look like:
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<TITLE>title here </TITLE>
some optional <META> statements.
Possible <SCRIPT> for Javascript.
</HEAD>
All your text and tags belong in between the <BODY> and </BODY>
Use of <FONT> didn't change anything.
If you were trying to change colors of text (or SIZE= or FACE=) using the <FONT> tag, make sure for every <FONT> you have a </FONT> and they enclose the text you wish to modify.

Symptom: Links Are Not Links (or Is Your URL Power Cord Connected?)

Link to another document is not working.
Chances are is is the same error as that of the <FONT> mistake. The </A> is in the wrong place. Remember, the syntax is:
<A HREF="blah blah">This is my link text</A>
Link to a position within a document takes me to the bottom (or top) of the requested document and not to the NAME= location.
This is sometimes a little trickier. First, remember the syntax. You must NAME the target area with a
<A NAME="somename">target text here</A>.
There is NO # in the NAME=. To link to the point where somename is, you need the # proceeding the anchor name,
<A HREF="#somename">Go Back</A>.
Remember, if somename is in a different document (different.html), the syntax is
<A HREF="different.html#somename">Go Back</A>.
Don't forget to check the case and spelling of somename.

Symptom: Images (or Links) Work For Me But No One Else (or Is Your Image Power Cord Connected?)

You see an image (or link works) but everyone says it doesn't.
Be careful that the URL specified in the <IMG> or <A HREF> does not include the file:// URL type. The file:// pulls the file from the client (your local machine) and not from a server. This actually has a use. If you have a file (a HTML page or image) that you only wish to use, you can use the file://. Remember, anyone else will get Error 404 - Document Not Found (someone is selling tee-shirts with that saying! I must get one of those!) or the broken image icon .
Make sure there is no DOS type pathname in the URL, such as C:\blah blah.
Certain client and server software will accept the \ (backslash) in addition to the / (forward slash) when specifying a URL path. Always use the /. It is the web standard.

Another problem could be the case (upper/lower) of the filename. Servers such as UNIX, have case-sensitive names. MyImage.gif, MYIMAGE.GIF and myimage.gif can be three different files. Always use lowercase (the typical UNIX convention) filenames for images and pages.

For links, the problem could be the extension. A file called mypage.htm make work fine when you test but the server may need mypage.html. In addition to FILE NOT FOUND, another symptom could be you document shows all the ugly HTML tags.

Symptom: Table Does Not Appear.(or Stop Using Your CD-ROM Drive As A Coffee Cup Holder)

Table colors are now supported by SOME browsers.
You do:
<BODY BGCOLOR="white" text="white">
followed by
<TABLE BGCOLOR="green" >
and the browser does not support table colors. Guess what, white on white!
Table does not appear.
I have had problems when I accidently deleted a </TABLE>. The table did not show up.
Surrounding a table with a font size.
The last time I checked, the font size was not obeyed inside the <TH></TH> or <TD></TD> containers.
If you can think of any other common errors that I may have missed, drop me a note at glassr@sunynassau.edu and I will try and add them.