Apache is a free and open-source cross-platform web server software.
PayPal is an online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like checks and money orders.
Plesk is a web hosting and server data centre automation software with a control panel developed for Linux and Windows-based retail hosting service providers.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.