This is an example of a simple .html file. The file name could end in .htm as well. (This is to accommodate operating systems which allow only three symbols after the dot in a file name.) Notice that this paragraph will be adjusted for different browsers and their settings! I am going to end this paragraph now.

You can see the marks which mark up the text by using the browser's view source button. You should do this now!

Notice that the end of paragraph mark is not necessary in early HTML. The next paragraph mark will imply the end of the earlier paragraph. In general, HTML is very forgiving! Newer developments are much less so, and so it is good to get in the habit of "doing it right."

Note that in HTML the marks can be either UPPER or lower case. In the newer XHTML they have to be lower case....
I just used a line break instead of a new paragraph symbol so that you could see it in action; it is good for things like addresses:
Hackensack High School
First & Beech Streets
Hackensack, New Jersey 07601

Now here is the hard rule:

The advantage of the preformatted mark is that you
can still use hyperlinks Return to index page
and  pictures in your page.
This is unlike the situation with .txt files.