Inverse Problems in Geophysics contains a detailed treatment on linear inverse problems in geophysics, as well as a description of the complications that arise in inverse problems due to non-linearity. A survey is given is of solving linear systems of equations. Poorly known pitfalls, such as the consistency problem and spectral leakage, are presented with simple examples. Seismology is based on three basis linearizations: the Born approximation, Fermat’s principle and Rayleigh’s principle. Each of these linearizations is derived in detail. In addition to the material on linear inverse problems an account is given how non-linearity complicates the process of inversion.