What does it really mean for a state to be in a superposition? Since a quantum information lecture today I have been wondering what does it really mean for a state to be in superposition? Is this something that is answerable?
This is what we learnt (or what I gathered :) ):
A classical bit is always in a state 0 or 1. Sometimes there exists a degree of uncertainty and so probabilities are assigned to either state but in reality it still is 0 or 1 right. However a qubit can be in a state 0, 1 or a superposition whereby this superposition is fundamentally different from the probability mixture for a classical bit. But how can this be so? Surely at any given time a system can in reality either be in the 0 or 1? Does it have something to do with the interference properties of the system?
If you could answer my questions and explain the fundamental differences between the qubit and the classical bit I would really appreciate it. Thanks!
 A: The state of a classical bit is one of the numbers {0,1}. Each measurement reveals the value of the state. 
The state of a qubit is a point on the 3-dimensional Bloch sphere. http://en.wikipedia.org/wiki/Bloch_sphere
Each measurement arrangement selects a particular point; the measurement then gives a value 1 with probability $\cos^2(\theta/2)$ and 0 with probability $\sin^2(\theta/2)$, where $\theta$ is the angle between the vectors from zero to the state point and the measurement point. 
In a coordinate representation, the qubit is described with respect to a particular measurement point (the north pole). The corresponding classical bit consists of the north pole and the south pole only. All other qubit states are superpositions of the two poles.
A: 
Surely at any given time a system can in reality either be in the 0 or 1?

Actually, no, that is not true. A quantum system can be in a state which is neither $\lvert 0\rangle$ nor $\lvert 1\rangle$; this is not possible with a classical bit. However, this state can be mathematically described as a linear combination of $\lvert 0\rangle$ and $\lvert 1\rangle$.
Consider the analogy of a traditional magnetic compass.

When the compass needle points north, that is like a qubit being in the state $\lvert 0\rangle$, and when the compass needle points east, that is like a qubit being in the state $\lvert 1\rangle$. But a compass needle can also point northeast. The direction northeast is neither north nor east, but it is a superposition of equal parts north and east: if you add a north-pointing vector and an east-pointing vector of equal magnitude, you will get a vector that points northeast. Similarly, the qubit state $\frac{1}{\sqrt{2}}(\lvert 0\rangle + \lvert 1\rangle)$ is neither $\lvert 0\rangle$ nor $\lvert 1\rangle$, but it is a superposition of equal parts $\lvert 0\rangle$ and $\lvert 1\rangle$.
A: bits are either zero or one if created specificially or measured.  when bits are randomly generated,  they are only a probability distribution until measured.  See  http://www.princeton.edu/~pear/ and their research with randomly generated bits.  
take a look:
http://www.princeton.edu/~pear/images/single-operator-graph.jpg 
