The laser-induced backside wet etching (LIBWE) is a promising technique for direct patterning of transparent materials with high quality. LIBWE causes laser etching at the back surface of the transparent sample that is in contact with an absorbing liquid. In this work, the etch process has been experimentally investigated to study the etch mechanism and ascertain the dominating processes at the backside etching of fused silica, glasses, quartz, MgF2, CaF2, and sapphire. Additionally, the fabrication of well-defined and high quality surface features into fused silica by LIBWE is demonstrated, which is potentially applicable for the shaping of microoptical components. The influence of process parameters on the etch rate and the surface quality have been systematically studied for LIBWE with organic solutions employing an excimer laser with nanosecond pulses. The main characteristics of the etching process are a specific and small etching threshold (about 0.33 J/cm² for fused silica), a small etch rate (1 to 20 nm/pulse), a small roughness of the etched surfaces (less than 10 nm rms), a certain etch efficiency, an incubation behavior, and a surface micro topography that depend on the etched material and the used organic liquid. The etched surfaces of fused silica samples have been analyzed with white light interference microscopy, SEM, AFM, Raman spectroscopy, XPS, RBS/channeling measurements, in situ reflection measurements, and UV/VIS transmission spectroscopy. The results show that a near surface region suffers from chemical and structural modifications that cause the alteration of the materials absorbance also at the used laser wavelengths. The irradiated liquid has been analyzed by means of GC-MS, Raman spectroscopy, SEM, and TEM. These results indicate to specific decomposition processes causing the formation of carbon products or even carbon. Based on correlations of the experimental results and physical models, the dominating processes are discussed, an improved model of LIBWE has been developed, and the temperatures at the interface have been computed. Recapitulating the influence of liquids decomposition and surface modification on the etch behavior and the temperature modeling material erosion in LIBWE follows a liquid-induced backside ablation mechanism.