Cloud computing is an on-demand service resource which includes applications to data centers on a pay-per-use basis. In order to allocate these resources properly and satisfy users’ demands, an efficient and flexible resource allocation mechanism is needed. Due to increasing user demand, the resource allocating process has become more challenging and difficult. One of the main focuses of research scholars is how to develop optimal solutions for this process. In this paper, a literature review on proposed dynamic resource allocation techniques is introduced.