For a project I am involved in I wanted to clarify the differences and similarities of {boQ} and {QaH}, so I asked Dr. Okrand for clarification. What follows is the complete and unedited response that he gave: Regarding {QaH} and {boQ} – There’s a good deal of overlap, and either one can be used in many (maybe most) situations. The main difference is really one of connotation. In general, {QaH} would be used in situations where the person needing help can’t do whatever needs to be done without assistance of some kind, while {boQ} would be used in situations where the person might be able to do the task alone, but it’s easier or better or more efficient if someone helps out. The object of {boQ} (the recipient of the aid) retains responsibility for the activity being aided. The person {boQ}-ing is secondary (though not necessarily unimportant!). The object of {QaH} can’t do whatever it is alone, so responsibility falls to the person {QaH}-ing (or responsibility is shared). Someone who falls into a river and is unable to swim would not shout out {HIboQ!}. Someone who can’t reach the top shelf would probably ask another person for {boQ} to get something down from the shelf (even though the task could be done alone if the person used a stepladder or stool or something). If the person tried it alone and boxes toppled down from the top shelf onto the person, immobilizing him/her, you’d probably hear the buried person ask for {QaH}. It would be odd to use {QaHwI’} to refer to an administrative aide; that’s a {boQ}. A parent probably wouldn’t {QaH} a child with a homework assignment. There is nothing weak about asking for {QaH} (when help is warranted), but an offer to {QaH} in a situation where you’d expect to hear an offer to {boQ} may sometimes be mildly insulting, implying that the offerer questions the offeree’s ability to do something. Having said all of that… The distinction is not always clear nor does it always matter, which is why the words are mostly interchangeable. "Assist” would probably be translated as {boQ} most of the time. Other than in a few contexts, both “help” and “aid” could be translated as either {boQ} or {QaH}. (David’s {boQwI’} app is aptly named.)