This paper presents an introduction to the current state of art of the Blockchain and Smart Contract technologies. Blockchain is a fast-disruptive technology becoming a key instrument in share economy. The Blockchain-based Smart Contract aim to automatically and securely execute the needed responsibilities of a contract without the support of a centralized execution authority. The Smart Contract runs on top of the Blockchain to facilitate, execute and enforce an agreement between un-trusted parties without the interfere of third party to trust it as this Smart Contract is an executable code that runs with rules on the Blockchain. Smart Contracts have some features that serve the goals of social justice and fairness. The paper presents the basic important information about the structures of the Blockchain and Smart Contract technologies and conduct a comparison between the different methodologies used in the Smart Contracts. The issues faced within the Smart Contract technology are surveyed. The four key issues are identified as: codifying, security, privacy and performance issues. We survey case cases of usage of the Blockchain in various business sectors like real estate, voting system and supply chain. The paper aims to assist a developer to grasp the big picture of the Blockchain technology and to further assist in the decision process of suitability of the technology to a specific application area.