WhatsApp Messenger is a freeware, cross-platform messaging and Voice over IP (VoIP) service owned by Facebook. It allows users to send text messages and voice messages, make voice and video calls, and share images, documents, user locations, and other media. WhatsApp's client application runs on mobile devices, but is also accessible from Windows and Mac desktop computers, as long as the user's mobile device remains connected to the Internet while they use the desktop app. The service requires users to provide a standard cellular mobile number for registering with the service. Users could originally communicate only with individuals or informal groups on WhatsApp, but in January 2018, WhatsApp released a standalone business app targeted at small business owners, called WhatsApp Business, to allow companies to communicate with customers who use the standard WhatsApp client.