The text file that is sent to the browser is written using a special language called HyperText Markup Language, or HTML. HTML instructions are referred to as tags. Tags are nothing more than a specific sequence of characters that define a container for some other text. The tags are placed on either side of some plain text and cause the browser to determine that the text denoted is not just plain text but that it is something special.

For example, if I wanted to write some text that you would interpret as a direct quote of something someone said, I would surround the text with quote characters ("").

Benjamin Franklin once said, "A penny saved is a penny earned."

Here I have quoted one of Benjamin Franklin's famous sayings. You can interpret the text between the quotes as his words, not mine. In this way, the text between the quotes has special meaning, and is interpreted differently than the other text.

HTML works in much the same way. The tags convey special meaning to the browser about the text between them. Tags almost always come in pairs. Although unlike the quote characters above, the beginning tag is written one way and the ending tag is written slightly differently. Let's say that I am writing my web page and I want to have some text appear in bold in the visitor's browser. The tags that define bold text begin with <b> and end with </b>. For example, in my HTML page I could type something like this:

One of my favorite historical figures is <b>Benjamin Franklin.</b>

Then when viewed in a browser, from the web server, it would appear this way:

One of my favorite historical figures is Benjamin Franklin.