Should I be using separate 'domain' layer?

** Mods, if for any reason this question is inappropriate, please leave a comment rather than putting it on hold and I will make the change according to your suggestion. Thank you.

I have been reading a lot about domain layer and DDD. However I am still confused about it. To me they seem to be a fancy name for business classes however more modelled towards your application domain but then most programmers I have worked with create business object/entities and try to model it as closely as possible to the actual application objects.

So here's the question. In the Asp.net Web API application whose primary focus would be to get large amounts data(GET requests mostly) from different tables on the basis of certain inputs and some logic running as a result, is there really a business need for Domain layer and objects? I am sorry for a very vague question but feel free to ask me for further details if it helps. Thanks all