In this talk, I will present a quantum algorithm known as quantum singular value transformation (QSVT), which applies polynomial transformations to the singular values of high-dimensional matrices. In Part 1, I will cover the mathematical preliminaries underlying the algorithm, including matrix decompositions (singular value decomposition and cosine-sine decomposition), the nonlinear Fourier transform, and selected results on uniform polynomial approximation. In Part 2, I will introduce the main components of the algorithm, including block encoding and quantum signal processing. As an application, I will describe a quantum linear system solver with optimal scaling in the condition number based on the block preconditioning technique, and discuss strategies to go beyond the condition number barrier.