While most Web pages are relatively stable, you may have some that change frequently. For example, you might have a page that dynamically displays your company's stock quote, changing on a minute-by-minute basis throughout the day.
Unfortunately, if the page is cached on the user's machine, more recent versions may never appear. What you need in this case is a way to tell the browser not to cache the page.
You can do this easily with a meta tag. Just add the following to the<head> section of your page:
<meta http-equiv="Pragma" content="no-cache">