Sometimes we need to have a static top and bottom with the rest space taken by the main content.

Most sites include a number of CSS and JavaScript files. Whilst developing it's usually easier to manage them as separate files but on a live site it makes sense to merge files to reduce the number of HTTP requests the browser has to make. For JavaScript this is particularly important as browsers block rendering whilst downloading.

To submit a form using POST method through PHP, just add the data to be posted as header. This essentially saves one extra html page sent to the browser when user has to be redirected. Mostly found this technique useful for redirecting to payment gateways.