What does "programming concepts" mean?

The question doesn't hinge on you understanding the difference between a technology and a concept. The question hinges on two things: is there anything going on in this industry that you think is worth "following" - whatever following might mean how clearly, accurately, and passionately do you talk about whatever that is It might be concurrency and parallel programming. It might be GPGPU programming. It might be programming for handheld devices. It might be moving everything to the cloud. It might be some new programming language and framework or platform you've been playing with in your free time. Once upon a time you might have been able to answer this with something about Agile, or Ruby on Rails, or web services. The key is that you don't give a one word or one sentence answer. I mean come on! You want to work in this industry, right? Why? The answer to this question should burst out of you. "X! Because X changes EVERYTHING and it's SO COOL and I remember when I first saw it I knew it would be great [or I didn't realize what it was] and then I started doing some of it myself [at home or after hours or on my second assignment] and wow oh wow I could see that [cool stuff about X] and now I read blogs about it, I follow [a,b and c] on Twitter, I went to all the X talks at [CodeCamp or whatever] and I just think it's the coolest thing!" Seriously, they offer you a chance to go all fanboy (or fangirl as appropriate) on the tech of your choice, and your response is "What? programming concepts aren't something you can follow! This question is ill formed." Don't do that. The interviewer is throwing you a giant softball. Hit it out of the park.

All three refer to the same things really. Threading can be described as a development concept, a topic or a range of technologies that make the concept real. What they are actually asking is what development related stuff are you interested in at the moment. Useful tip: If an interviewer asks you something that you don't understand, it is ok to get clarification. I actually ask questions which are barely coherent just to see if the candidate will try to get clarification or will struggle to answer a question that is clearly gibberish.

Replace the word "following" with "practicing or trying to gain deep understand of"

I know what programming technologies are—C#, Java, .NET, etc—but what are programming topics and concepts? You could look at software development methodologies or project management methodologies used in software like Agile, Scrum, XP, Pair-programming, various driven-development models like TDD, BDD, DDD, etc. The key here is what areas of development are you studying in terms of gaining a greater understanding. How is Saas impacting your development? How does the paradigm of distributed version control differ from a centralized repository model? What are you getting to know? How are you doing that? What resources are you using to advance yourself? Those are the kinds of questions that you can apply to any tool, practice, strategy, or thought within software development. You could even take off-shoring or outsourcing as topics to consider within programming.