[hxa7241]

What is abstraction? Here is an informal casual answer that works quite well.

An abstraction unites something fixed with something varying. It specifies something fixed that ecompasses a set of variants.

For example, an 8 bit number fits this straightforwardly. The number of bits and their interpretation as successive powers of 2 is what is fixed; the actual values of the bits is what varies.

It seems quite a good definition: it is simple, and discrete -- it is measurable, and it very neatly fits software/computation. It is pretty much built-in to the basics of what we commonly take as computation, the bit -- a single element (fixed) with two values (varying between 0 or 1). And everything follows on top of that.

And furthermore, this definition can even be seen as somehow quasi-fundamental, as inevitably arising in how natural systems behave (well, with a little imagination maybe -- it is worth a ponder) . . .

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