Theoretical approaches to the spatial structure of linear macromolecular chains are reviewed. The associated problems are found to be essentially different when repulsion and attraction between chain elements are respectively dominant. In the case of attraction, the chain condenses on itself and forms a globule with a definite structure which can be analyzed in the self-consistent field approximation. In the case of repulsion, the result is a coil with a fluctuating structure and, in this situation, one must use the methods of scaling theory. The coil-globule transition is also analyzed.