eBay Partner Network is an online referral program where eBay pays commissions to referrers on sales generated by customers they’ve referred.
Google AdSense is a program run by Google through which website publishers serve advertisements that are targeted to the site content and audience.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
PHP is a general-purpose scripting language used for web development.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.