Abstract: Previous studies of galaxy formation have shown that only 10 per cent of the baryons are in compact  objects, while 90 per cent of them are missing. Numerical simulation shows that the missing baryons are in a state of diffuse plasma with temperature 10^5 to 10^7 Kevlin, which is hard to be detected by X-ray observations. I will present three studies that coherently detect the missing baryons and reveal the temperature of the intergalactic medium. These include the thermal Sunyaev-Zeldovich effect, kinetic Sunyaev-Zeldovich effect and weak lensing.