This article provides a general review of the epitaxial lateral overgrowth (ELO) technology and of application of ELO layers as substrates with adjustable value of lattice constant. In particular, the issues of ELO growth mechanism, substrate defect C, filtration during ELO procedure and strain in ELO layers will be addressed. Recent literature data on MOVPE ELO growth of GaN on sapphire and our results on lateral overgrowth of GaAs on GaAs and Si substrates by LPE are used as examples. Finally, other lateral overgrowth techniques (growth of lattice mismatched bridge layers and pendeo-epitaxy) will be presented and 41 compared with the conventional ELO technique.