The book systematically accounts for the scientific and technological problems of nanostructured silicon in the form of porous and black silicon.  Nanostructured silicon is currently a pioneer research topic worldwide due to its enormous potential applications for modern electronic devices, such as sensitive photodetectors, solar cells, biochemical sensors, hydrogen generators, and display devices. The main structural modifications of this nanomaterial are porous and black silicon. Porous silicon addresses crystalline silicon with nanopores and black silicon with nanoneedles.  Historically, porous silicon is thought to be a kind of precursor to black silicon.  The formation, research, and application of nanostructured silicon remains the main cornerstone of nanotechnologies, and this book is useful for a wide range of researchers in the fields of semiconductor physics, micro-, and nanoelectronics.   The author outlines the prospect of black silicon fabrication and its various applications.  As for porous silicon, the book contains a detailed analysis of this material as a precursor of black silicon. This allows it to be possible to carry out correlations between two structural modifications of nanostructured silicon to clearly and reasonably show their advantages and disadvantages. With many references to a vast resource of recently published literature, this book serves as an important and insightful source of valuable information and provides scientists and engineers with new ideas to better understand the formation processes of nanostructured silicon as well as improve and expand their properties.