Formal "Hello":
* "Hello" sign: The most common way to sign "hello" is with the "H" handshape (index finger and thumb extended, other fingers closed) and moving it from your forehead out in front of you, palm facing outwards.
Informal "Hi":
* "Hi" sign: This sign uses the "Y" handshape (index and pinky fingers extended, other fingers closed) and is waved from side to side in front of your face, palm facing outwards. This is more casual and is often used with friends and family.
Other options:
* "What's up?" sign: This sign is made with a "W" handshape (all fingers extended and spread) and is moved up and down in front of your face. This is a more informal greeting, similar to "What's up?".
* "Good morning/afternoon/evening" signs: You can also sign a greeting depending on the time of day. These signs are made with a "G" handshape (thumb and index finger forming a "C" shape, other fingers closed) and are moved slightly forward in front of you.
Remember that these are just a few examples, and the best way to learn how to sign "hi" is to find a qualified ASL instructor or learn from resources specifically focused on ASL.