Going back as far as at least the 1400s, words like “hollo” and “holla” were used in England. A speaker shouted them out when they needed to get attention fast, sort of like, “Hey everybody, look at this!” Like many very old English words, hollo has its roots in an Old German word, holon, which technically means “to fetch,” but was most used to hail a ferryman. In England and English, its use remained the same well into the 1800s: as a call of urgency. But by then, it had evolved into “hullo,” and in American English into “hello.” It only took off in popularity as a casual greeting when it became the most common way to introduce oneself at the beginning of conservations held via that new to the late 1800s invention: the telephone. (It beats telephone inventor Alexander Graham Bell’s suggestion of “ahoy.”)
Around the same time that hello was becoming a common American greeting, “hi” appeared, too. Its origin and development were completely separate from that of hello, but it’s a similar story. As “hollo” meant “hey!” “hi” was actually a corruption of “hey!” Its first printed use occurred in 1862.
Most commonly associated with the South, particularly Texas, or friendly cowboys, “howdy” is a casual, friendly greeting. Indeed, it made its first appearance in written form in the mid-19th century as an example word of the Southern dialect. But it’s actually a version of another, older phrase. It’s a shortening, or contraction from “How do ye?” a greeting used by Scottish and Irish immigrants who’d settled in the U.S., particularly in the South and West. That phrase is, in turn, a shortening of the more formal “how do you do?” In other words, “how do you do?” became “how do ye?” and in a Scottish brogue, over time, that became “howdy.”