You seem to imply that abstract data types and data structures are in some way similar (or related). It's not the case; an ADT is not a kind of, nor an alternat

You seem to imply that abstract data types and data structures are in some way similar (or related). It's not the case; an ADT is not a kind of, nor an alternative to, a data structure (and vice versa). They are different things for different purposes, just like an algorithm isn't the same thing as a data structure. I acknowledge that their names can be confusing (both contain the word "data"). "data structure" isn't a bad name; we understand that it's about how data is organized. But "abstract data type" is less clear, indeed. edit: I think I found what may confuse you: I guess it's a visualization problem. When you're visualizing a data structure, it probably looks like boxes connected to each other with arcs. And I think your book has nice pictures for ADTs, too (stacks, queues, etc. drawn using boxes and maybe arcs as well). Whereas it's clear that an algorithm is very different from a data structure because it's described using pseudo-code. Forget the graphical representation for ADTs; think of them instead as a list of "rules" of the form "when I dequeue something from a queue, I get the last item that was enqueued".