A great piece of advice for online dating is to stand out from the crowd. So greetings like "hello" and "hi" are very common. They do less well than things that are a little bit quirky or a little bit weird, like "howdy" or "holla. " The rarer your salutation, the better it does, in general.
Knowledge is not eating, and we cannot expect to devour and possess what we mean. Knowledge is recognition of something absent; it is a salutation, not an embrace.