Hello - The Origin
Hello" has only been used since the late 1820s. According to the Oxford English Dictionary, the first published use of hello was in 1827. However, at that time it was not used mainly as a greeting; instead hello was used either to to show surprise (eg - Hello, what happened to that house?) or get someone's attention (eg - Hello, what are you doing?).
Though the exact origins of hello are not clear, this usage might originate from the fact that hello probably developed from words in Old High German - hallo and hollo, which mean “to fetch" and shouted during a hunt when prey was spotted and French - holla or hola, which mean “whoa there!"). Some also believe that hello came from the word "hullo", which was a British word used to express surprise,greet a person or to draw attention. Bill Bryson (the author) believes that hello came from the Old English phrase hál béo þu, which meant "whole be thou." This phrase was used to wish someone good health.
But this is not it. There is more to the journey.
Hello wasn't used as a greeting until when the telephone was invented. The inventor, Thomas Edison is said to have suggeted the use of hello as a standard greeting when answering a telephone. His competitor - Alexander Graham Bell preferred the word “ahoy." While ahoy may make us feel like a pirate today, the word actually had been used as a greeting for a long time among sailors. He liked the word so much that he continued to answer the telephone that way his whole life.
Hello eventually came to be used as a greeting and historians credit hello's rise to the first telephone books. Since people were unfamiliar with these new devices, telephone books contained detailed instructions regarding proper telephone use. They recommended the greeting "Hello" and hence it was used in huge numbers.