“Go Back” Button

1. Browsers already have "back" buttons, so you'd better have a darn good reason for needing to put one on your page!
2.  
3. Input button with inline JavaScript
4. <input type="button" value="Go Back From Whence You Came!" onclick="history.back(-1)" />
5.  
6. This is totally obtrusive, but you could fix that by only appending this button through JavaScript.
7.  
8. PHP
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10. If JavaScript isn't a possibility, you could use the HTTP_REFERER, sanitize it, and echo it out via PHP.
    
    
11. <?php
12. $url = htmlspecialchars($_SERVER['HTTP_REFERER']);
13. echo "<a href='$url'>back</a>";
14. ?>