To prevent the caching of a web page on your client's end, use the following snippet of PHP to ensure that the appropriate HTTP headers are sent.
PHP:
The first header tells the client that the page must not be cached.
The second header is a backup, and tells the client that the page expired a long time ago in the past, and it should fetch a more recent version.
The same effect can be achieved by placing corresponding meta tags in your HTML document
HTML:
Where possible, place your cache control directives in the HTTP header, because some clients and proxies rely on your server's HTTP response to determine caching.
