This is presuming that you're a young person. Depending on your country and culture, common etiquette would mandate that you say 'How do you do?' Alternatively, if you're simply walking past someone you wish to acknowledge, you may say 'good afternoon, good morning, or good evening,'
If the introduction is more formal, it may be appropriate to say 'how do you do? It's a pleasure to meet you.'
bonjour
There's no difference in saying "hallo" to a child or to an adult but you could say "Guten Tag"
bonjour monsieur / bonjour madame comment allez vous
You say "hello" in English.
You say anyung or anyunghasehyo. Anyung means hi to a friend or someone close to your age. Anyunghasehyo means hello to an adult. usually people bow when their saying hello in Korea to an adult
Say Hello to Rosita!
Kamusta is how you say hello
halito is how you say hello and how to say hello how are you is Halito, Chim Achukma?
This is how you say hello in Turkish: Merhaba = Hello
Crocodiles do NOT say hello.
In Neapolitan, you say "ciao" to say hello.
In Paiute, you can say "Kwai" to say hello.