Your mobile device must be connected to the Internet and the WhatsApp app should be installed on it for WhatsApp Web to work.There is a small setup process that you must follow and keep certain things in mind before you can use WhatsApp Web. However, the process to use WhatsApp Web on your PC is not as seamless as using Hangouts or iMessage on your PC.
Earlier today, WhatsApp announced a web version of their client, dubbed WhatsApp Web, allowing its users to chat with their friends and relatives right from the comfort of their PC.