There are many ways to greet people in English. Some ways are formal and others are informal. Formal greetings are used when you don't know a person very well or when you are in a formal setting like a job interview. Informal greetings should only be used with close relatives and good friends. Some popular greetings are: Hello, Hi, How are you?, What's up?, What's going on?, How's it going?, Good morning, Good afternoon, and Good evening. (3-page lesson)
The most common greeting in English is "Hello".
Saying hello is correct for both formal and informal situations.
"Hi" is less formal than hello.
Saying hi can be used in both formal and informal settings, but it is always safer to say hello if you're not sure which greeting to use.
Remember to smile when you say hello!