You Alright?

1) A common UK greeting synonymous with hello or yo. Similar to how's it goin? or what's up? Though often inflected with an upspeak, suggesting a response is required. It isn't necessarily, and if the person then wants to talk about what so-and-so said to so-and-so near the printer today. It can be downright unwanted!

2) A genuine concern for a persons well-being where a response is required. The person could be recently bereaved or long since last seen.

Context is important. If the person was seen half an hour ago and there's no reason to think they're in any distress, it's a greeting. When confronting an injured person, it requires a response.

You alright?