One of the best ways to get to know someone is to just say hello. This may seem like an obvious method, but saying hello to someone differs from country to country, and even from region to region in the same country. In the United States, people are informal when meeting other people for the most part. Saying hello tells you a lot about the person you are greeting, and it also tells that person something about you. Typical greetings are "hello, hi, greetings, good day, good morning, or good afternoon or evening." With the exception of hi, all of these greetings can be considered formal greetings that are universally understood in the United States.
Some of the more informal greetings vary greatly from person to person. Younger people have created their own slang for greeting someone, and the slang is constantly changing. For instance, the term "what's happening" was very popular during the 1970s and 80s, and it is still in use today, but it has been replaced by several other greetings by the newer generations. "What's up, or wass up" can be heard frequently in the U.S. among the younger people. These two terms are considered informal greetings that a person should never use in a formal setting. These terms are usually reserved for informal encounters and are usually said by friends.
When a person says hello to another person, it says a lot about that person. It conveys a friendly attitude and a willingness to get to know the other person. It can mean that the person initiating the conversation is someone who likes to socialize, or just likes people in general. If the greeting is accompanied by a smile, it is all the better.