This chapter provides a basic overview of SAXS and SANS techniques, which includes definitions of the basic notions, description of main properties of x-rays and neutrons, a general mathematical background which describes the physical processes in a scattering experiment, and main procedures in experimental data analysis and extraction of structural parameters. We also present derivation of form factors of basic Euclidean shapes which will form the basic units of the fractals introduced thereafter, and describe the main numerical methods for calculating the scattering intensity when analytic form factors are not available. Although, in principle SAS with light (SALS) and with fast electrons (SAES) is also possible, we intentionally omit their discussion here since SALS can not be used for non-transparent samples while SAES requires large wavelengths.