Abstarct: Quantum teleportation is one of the important concepts in quantum information and computation. In this study, different aspects of the quantum entanglement and teleportation are studied. First, entanglement and maximally entangled states are studied and some different measures of entanglement are introduced. Furthermore, the simple form of teleportation which exploits two entangled qubits as quantum channel, is discussed. Teleportation in higher dimensions has the ability to send more information and also is more robust than lower dimensional teleportation in the case of noisy channels. So, higher dimensional teleportation is studied as well. Finally, necessary and sufficient conditions for the teleportation of an unknown qubit with n-qubits entangled state are discussed.