Stray capacitance

[Kipper4]

I've seen this in a couple of threads now and again and I don't understand it.
Would someone care to explain it to a layman?
Where , when, how, why etc
Thanks
Rich

[ashcat_lt]

A capacitor is two conductors with space between them.  In the real world every conductor is separated from every other conductor by some space, and therefore it can be said that everything is capacitively coupled to everything else.  Basically, any capacitance which couples two conductors to one another which you did not purposely add to the circuit is a stray capacitance. 

[R.G.]

Ashcat got it right.

In theory, everything in the entire universe is capacitively coupled to everything else.

In practice, the actual value of the capacitance decreases kind-of linearly with decreasing surface area of the two conductors, and with the square of the distance. That inversely-with-the-square-of-the-distance thing is a biggie. For the small (tiny!) voltages and objects we deal with, you can probably ignore any capacitance for wires separated by more than a meter.

But when you go stuffing lots of wires inside a small box, using high impedance amplifiers with responses up into the FM or cell phone bands, things can get ugly.

[Kipper4]

Thanks Ashcat and RG
I get it now.
After reading electrical engineering through one time only so far. One of the things that stuck in my mind is that every componants has a resistance,induction and capacitance.
I have a lot more reading to do and I'm learning all the time. This brings me great joy.
I'm hoping the kids will get me RG's book for Christmas too.
Thanks for helping me out.
Thanks Aron to for this forum.