Is a simple circuit series or parallel? Suppose we have a  simple circuit in which a battery is connected to only one resistor.  Is this considered as series or parallel?

 A: They share the same current so you could call it series. They share the same voltage so you could call it parallel.
But whatever you call it is irrelevant. There is only one resistor so you cannot simplify the circuit any further regardless of what you call it. Calling it one or the other gives you no formulas to use or insights or simplifications. It is irrelevant to anything so call it either or both or neither.
A: What you call them may be important in a conversation.
Let's say you're at a party trying to explain an electrical circuit to a girl.

*

*If you tell her "Imagine a battery and an LED connected in series" she might think of this



*If you tell her "Imagine a battery and an LED connected in parallel" she might think of this 


*If you tell her "Imagine a battery and an LED connected neither in series nor in parallel" she might think of a star connection or who knows what, be a little confused, and ask for clarification



*If you tell her "Imagine a battery and an LED connected both in series and parallel at the same time", again she might be confused and ask for clarification.
You may simply call it "an LED connected to a battery" and most people will just think of the simple circuit, without being confused whether is series or parallel.
