A review of e+e- Linear Colliders

There is a strong interest of the physics community to study the physics of e+e− interactions at CM energies well beyond the reach of LEP. The hope is to find and study the Higgs particle and supersymmetric particles. CM energies of order 500 GeV will be needed to look for new interesting physics [1]. Energies in that range are not accessible by e+e− storage rings any more. The product of radiated power by synchrotron radiation Pb and bending radius of the magnets ρ scales as [2]