WhatsApp uses an advanced cloud-based infrastructure, with user data stored in multiple data centers located around the world. This allows it to maintain an efficient and reliable communication service. WhatsApp also uses basic elements of internet connectivity such as servers, networks, and hardware to provide a secure and reliable platform for messaging services. It uses the Signal Protocol for end-to-end encryption of all messages, ensuring that only the sender and recipient are able to read them. Additionally, it uses Voice over Internet Protocol (VoIP) for voice and video calling, and employs virtual SIM technology to enable users to make and receive calls internationally.