PHP is a powerful open source server-sided scripting language that can be used on a wide variety of operating systems and webservers, including Apache on UNIX and IIS on Windows.
PHP contains numerous extensions which enable you to dynamically create images and flash files, parse xml, connect to remote servers using pop, imap, ftp, http and raw sockets, natively access many database servers including PostgreSql, MySQL and Microsoft SQL Server, compress and decompress files, lookup domain names and and much more.
PHP has an excellent manual and online documentation which covers every function for every extension available.
The geoip_* PHP functions utilise the GeoIP library from Maxmind to geolocate IP addresses to country names. These functions are not enabled by default and this post shows how to enable them for PHP 5 on Debian 5.
I recently posted how to do geo targeting with PHP with the GeoIP functions but discovered when testing something today that PHP throws an E_NOTICE notice error if the IP address does not exist in the database.
The PHP CURL functions use the libcurl library to allow you to connect to various servers and different protocols. If the http referer string is not explicitly defined then nothing will be sent to the web server, but there may be times when you need to pass this along with your request.
PHP’s CURL functions make it easy to download content from websites. Sometimes you need to be able to manage cookies set from the site the data is coming from. This is done using the CURLOPT_COOKIEJAR and CURLOPT_COOKIEFILE options as shown in this post.
If you’re using a Javascript library like jQuery it’s likely you’ll end up with many Javascript files that need to be included in each page request. Ideally these should be combined into a single file and minified to cut down on page load time. This post shows how to use jsmin-phpto combine multiple Javascript files into a single minified file.
The PHP GeoIP library makes it easy to look up country codes and names from an IP address. It’s not enabled/installed by default so you need to install it before you can access these functions. I’ve already posted about how to do this with Debian and other Linux distros will be similar.