Transparent brittle materials such as glass and sapphire are widely concerned and applied in consumer electronics, optoelectronic devices, etc. due to their excellent physical and chemical stability and high transparency. Laser induced backside wet/dry etching (LIBWE or LIBDE) refers to the technique of applying absorber (liquid or solid layers) on the rear surface of workpiece and then focusing the beam on the liquid-solid interface for machining. High aspect ratio microgrooves and various microstructure are fabricated on glass and sapphire substrates quickly and accurately, which has been proved to be an effective and flexible way to process all kinds of transparent brittle materials with high-precision and highquality. The removal mechanism and model are revealed by considering the physical phenomenon like plasma, cavitation, micro-jet, etc. Additionally, applications of these techniques in micromachining, patterning, microfluidic, and microcircuit are introduced in detail.