Viber is a free messaging and calling app that allows users to communicate over the internet. It enables users to send text messages, make voice and video calls, and share photos and files with friends and family. Viber is available on various platforms, including smartphones, tablets, and computers, making it easy to stay connected across devices. The app uses a phone number for registration, linking it to the user's contacts. Viber also offers features like group chats, stickers, and the ability to call non-Viber users for a fee. It prioritizes user privacy with end-to-end encryption for messages and calls.