  We present a multipartite entanglement measure for $N$-qubit pure states,
using the norm of the correlation tensor which occurs in the Bloch
representation of the state. We compute this measure for several important
classes of $N$-qubit pure states such as GHZ states, W states and their
superpositions. We compute this measure for interesting applications like one
dimensional Heisenberg antiferromagnet. We use this measure to follow the
entanglement dynamics of Grover's algorithm. We prove that this measure
possesses almost all the properties expected of a good entanglement measure,
including monotonicity. Finally, we extend this measure to $N$-qubit mixed
states via convex roof construction and establish its various properties,
including its monotonicity. We also introduce a related measure which has all
properties of the above measure and is also additive.
