With the advances in ICT infrastructure, a new technology has emerged, that is cloud computing. Cloud computing is one of the most significant technologies enabling companies to manage their resources, and to save and share data safely through the internet. Choosing the right cloud-computing platform, which meets the company's needs, is not easy to handle task. In this Paper, the main three cloud computing platforms, namely, Google, Microsoft, and Amazon, were studied. Also, these platforms were compared and classified according to the possibilities they offer. This study aims at helping companies to choose the right cloud-computing platform, which meets their needs and requirements.