utomated telephone directory activated by voice commands. Used by telephone companies for directory assistance and by large corporations such as airlines, which use it for reservation systems. Online advertising software. Skype and Microsoft Teams are the most widely used services worldwide for making international voice calls and audio and video conferences. Twitter An international specialized social network, Twitter is another form of social networking. People use Twitter to broadcast microblogs, or "tweets," of not more than 280 www.TechnicalPDF.com characters to others who "follow" them. Many celebrities and most businesses have a presence on Twitter. They use it to post timely information about their business and for public relations purposes. Interestingly, Twitter is used more by people older than 25 than by teens, who mainly use Snapchat and sometimes Instagram. Twitter also streams live events including inaugurations and sporting events. It includes a "Moments" section with photos and updates about celebrities and current events. Users tweet comments on the news and celebrity updates in Moments. Commercial organizations use both Facebook and Twitter to promote their products and to monitor people's reactions to their products and services. In addition to public relations benefits, feedback on social networks enables businesses to react more quickly to complaints or to learn how to improve their products. It also enables non-profits to conduct fund-raising efforts and candidates for public office to gain a following. Twitter is a public company with 2018 first quarter revenue of $731.6 million. The majority of Twitter's revenue is from advertising on its sites and the rest from licensing fees. Apple Apple, Inc., is the world's most valuable company. It develops both the hardware specifications and operating system software on its Apple Watches, Apple TV, smartphones, desktop computers, Home Ped home automation, laptops, tablets, and Wi-Fi routers. To a large extent, it also controls the applications that