Real schematic vs. ideal schematic, real components (R, L, C) vs. ideal components
This may seem an evasive answer, but there is no 'realness'. Everything we use is an abstraction, which is an approximation of the the lower abstraction underneath it. 

This goes all the way to down to Schrödinger equations that describe the world perfectly as far as we know today (which probably just means that there are lower layers that we don't know about yet), but which we can't solve for any but the most simple situations.

The trick is to know the abstraction that you are using, to know when it falls apart, and avoid such situations.

It is for instance much easier to work with ideal logical gates (no delay, no power used, ideal waveforms, etc) and to make sure that they


are used well below their maximum speed
are adequately powered and decoupled
are connected by wires that are short compared to the waveforms and switching times


For the much rarer cases, or the much smaller parts of your design, where these conditions are not met, you must look much more careful and see the logical gates and their interconnecting wires as sources with a certain impedance, tranmission lines, and you might need receiver sides that have a well-known impedance (much lower than you would prefer in the 'ideal' situation). Yuk.

Most designers can cope with one or a few abstraction levels. I can deal with all kinds of layers in software. In hardware I can deal with logic, gate delays, and I can apply enough rules of thumb to avoid getting in all sorts of problems at this level. One level down I can make good guesses, but I must leave the real work to the experts at that level (who should probably not diddle too much with the higher software layers that I am more familiar with).

If I want a taste of the real deep down level I can always ask my wife about interactions of bosons as described by path integrals. Probably a much more accurate description of the physical world, but not very applicable to everyday electronics.

The unofficial bible of electronics (Horowitz &amp; Hill) does an adequate job of explaining a few layers of abstraction that are useful in electronics design, including the limitations of these abstractions.


(thanks Phil - I LOVE xkcd!)