Always check the value before using it.
This way you can make sure the value is valid.
If you know the choices, do not use it directly. Use an array instead.
To have your files deflated in apache you can add these lines to your .htassecc file.
Deflating files helps keeping transferring size small. Apache automatically pack the files and your browser unpacks it but the you can save lots of MB a year on transfer size. And it helps the site to load faster on slow connections. This is almost like gziping but deflating method is less CPU aggressive on apache server compared to gzip.
To put expiredate on your files you can put these lines to your .htaccess file.
It reduses loading time for your site.
To put gzip on files from apache server you have to add there lines to your .htaccess file.
