The variational method complemented with the use of explicitly correlated Gaussian basis functions
is one of the most powerful approaches currently used for calculating the properties of few-body
systems. Despite its conceptual simplicity, the method offers great flexibility, high accuracy, and can
be used to study diverse quantum systems, ranging from small atoms and molecules to light nuclei,
hadrons, quantum dots, and Efimov systems. The basic theoretical foundations are discussed, recent
advances in the applications of explicitly correlated Gaussians in physics and chemistry are
reviewed, and the strengths and weaknesses of the explicitly correlated Gaussians approach are
compared with other few-body technique
