The word bot, in Internet sense, is a short form of robot and originates from XX century. The modern use of the word bot has curious affinities with earlier uses, e.g. “parasitical worm or maggot” (1520s), of unknown origin; and Australian-New Zealand slang “worthless, troublesome person” (World War I -era). The method of minting new slang by clipping the heads off respectable words does not seem to be old or widespread in English. Examples: za from pizza, zels from pretzels, rents from parents, are American English student or teen slang and seem to date back no further than late 1960s.
Companies use internet bots to increase online engagement and streamline communication. Companies often use bots to cut down on cost, instead of employing people to communicate with consumers, companies have developed new ways to be efficient. These chatbots are used to answer customers' questions. For example, Domino's has developed a chatbot that can take orders via Facebook Messenger. Chatbots allow companies to allocate their employees' time to more important things.
Of course, each messaging app has its own fine print for bots. For example, on Messenger a brand can send a message only if the user prompted the conversation, and if the user doesn't find value and opt to receive future notifications within those first 24 hours, there's no future communication. But to be honest, that's not enough to eradicate the threat of bad bots.
According to the Journal of Medical Internet Research, "Chatbots are [...] increasingly used in particular for mental health applications, prevention and behavior change applications (such as smoking cessation or physical activity interventions).". They have been shown to serve as a cost-effective and accessible therapeutic agents for indications such as depression and anxiety. A conversational agent called Woebot has been shown to significantly reduce depression in young adults.
“We believe that you don’t need to know how to program to build a bot, that’s what inspired us at Chatfuel a year ago when we started bot builder. We noticed bots becoming hyper-local, i.e. a bot for a soccer team to keep in touch with fans or a small art community bot. Bots are efficient and when you let anyone create them easily magic happens.” — Dmitrii Dumik, Founder of Chatfuel